STRATEGIC BOMBING IN WORLD WAR I1
AIRPOWER had a mighty vindication in World War 11.
AIRPOWER had a mighty vindication in World War 11.
brodie-strategic-bombing-in-ww2
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STRATEGIC BOMBING IN WORLD WAR I1
AIRPOWER had a mighty vindication in World War 11. But it was Mitchell's conception of it-"anything that flies"- rather than Douhet's that was vindicated. It was in tactical employment that success was most spectacular and that the air forces won the unqualified respect and admiration of the older services. By contrast, the purely strategic successes, however far-reaching in particular instances, were never completely convincing to uncommitted observers. Against Germany they came too late to have a clearly decisive effect; against Japan they were imposed on an enemy already prostrated by other forms of war. If airmen were like labora- tory animals running a maze, they would seek to repeat
successes and to recoil from frustrations. They would now be all in favor of tactical as against strategic uses of air power. But being instead very human, and knowing also the power
of nuclear weapons, they have remained intensely loyal to ! their original strategic ideas.
The conditions of any future war in which nuclear weap- ons are used will be critically different from those of World War I1 in almost every significant respect. Nevertheless, because the experience of World War I1 is often appealed to as having "proved" this or that about air power, there is value in summarizing that experience briefly and objectively. It is, for all practical purposes, the only experience we have with strategic bombing. Small wonder that it has influenced importantly the ideas we still carry around on the subject,
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
especially with respect to the amount of destruction neces- sary to win a war by strategic bombing.
The Allied strategic bombing campaigns against Germany and Japan in World War I1 are, despite their complexity and magnitude, among the most brilliantly illuminated military campaigns of all time. The United States Strategic Bombing Survey (U. S. S. B. S. ) carried out its survey of Allied bombing in Europe on the heels of the advancing Allied armies, in the hope of applying the resulting lessons to the strategic bombing of Japan. However, the victory over Japan fol- lowed soon thereafter, and the Survey organization pro-
ceeded at once to make a comparable study of the campaign against Japan.
The resulting work comprises 208 separate published items for the European war and 108 items for the Pacific war. The Survey staff was in most fields marked by very high com- petence and talent, and the manner in which the members were selected provided about as good a guarantee against bias as could be found. There were also some complementary studies carried on by other organizations or individuals, some of which benefited from being under less pressure of
time than was imposed on the authors of the Survey. ' Thus,
lThe British work most nearly comparable to the U. S. S. B. S. is that by the British Bombing Survey Unit (called during the war the RAF Bombing Analysis Unit). However, the publications of that organization- most of them classified-have had only the most limited distribution within the United States. The basic volume in the series is entitled The Strategic Air War Against Germany, 1939-45. In America, there have been some distinctive publications (also originally classified) by an agency of the Air Force called the AAF Evaluation Board, which was rather more con- cerned with tactical targets and operations, such as those incident to the Normandy landing, than with strategic air operations. The British Bomb- ing Survey Unit tended to straddle both strategic and tactical operations. It was, unlike the other surveys mentioned, very largely directed by persons who had made heavy commitments to operational decisions. With respect
the relevant facts of any importance are available. All one has to do is read the appropriate publications carefully with an open mind.
The Attack on the German War Economy
With respect to the German campaign, study of the survey findings leads to three major conclusions: (I) our strategic bombing brougnt the German war economy to the point of collapse; (2) that result came very late in the war, too late to develop its full potential effects on the ground and naval campaigns, which were already proceeding to a decisive con- clusion; and (3) given only the air power actually in Allied hands, but assuming better understanding of the capabilities of strategic bombing and especially a wiser choice of targets, the positive results achieved by bombing could have come much sooner than they did. Had they come sooner by six months, their beneficial influence for shortening the war and saving Allied lives would have been unequivocal.
Let us examine the first conclusion. The oft-repeated argu- ment, based on U. S. S. B. S. statistics, that German war produc- tion in almost all categories increased drastically between the middle of 1942 and the middle of 1944, is beside the point, because the scale of bombing which brought about the final significant results had barely begun by mid-1944. The weight
--
to targets within France, one must mention also the work of the French Operational Research Group.
The general, semi-officialhistories which might be studied in conjunction with the abovezited reports are, for the United States, W. F. Craven and J. L. Cate, The Army Air Forces in World War 11, 7 vols. , University of Chicago Press, Chicago, 1948-1955;and for the British, Denis Richards and Hilary St. George Saunders, Royal Air Force, 1939-1945, 3 vols. , H. M. Stationery Office, London, 1953-1954. See also Burton H. Klein, Germany's Economic Preparations For War, Harvard University Press, Cambridge, '959.
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of Allied attack, which in 1942 averaged under 6,000 tons
monthly, rose in 1944 to an average of 131,000 tons monthly-
a more than twenty fold increase. The greategt rate of in- crease occurred just prior to the Normandy invasion, which itself absorbed in tactical operations for many months the major part of our strategic-bombing capabilities. Along with this increase in tonnage of bombs dropped came a great im- provement in operational techniques, especially in the use of radio direction devices. And beginning only in February
1944, large numbers of P-51 long-range fighters became avail- able for escorting bomber sorties practically anywhere within Germany.
Also, until mid-1942 the German war economy contained a large amount of slack. Contrary to general opinion, that economy was far from fully mobilized for war either in the kind of commodities produced or in the rate of production. The labor force was essentially on a single-shift basis and in- cluded relatively few women. The great increases in German war production over the next two years, despite our bomb- ing, resulted mostly from the taking up of this slack. Even so, judged by the standard of British industrial mobilization,
the German economy never attained anything like its full war potential. '
In any case, from our point of view it would not matter whether or not production as a whole diminished if the Germans had been denied even one truly indispensable war commodity, such as liquid fuel. In the final stages of the war, that is just what happened. Allied bombers knocked out the German industries producing liquid fuels and chemicals.
2 See U. S. S. B. S. , The Effects of Strategic Bombing on the German War Economy (Item #3 for European War), especially pp. 6-11. See also Klein, 0p. d.
I n an overlapping campaign they also effectively knocked out the German transportation services, upon which everything else depended.
German oil-production facilities were recommended as a top-priority target on March 5, 1944, and oficially designated as such in a directive of June 8, two days after the Normandy landing. There had meanwhile been two days of attacks on the industry during May, but the full-scale attack started at the end of June and continued until March 1945. There were 555 separate attacks on 135 different targets, including every synthetic-fuelplant and major refinery known to be in oper-
ation.
The beginning of the onslaught started a precipitous drop
in German oil production. From an average of 662,000 tons per month, it went down to 422,000 tons in June, z60,ooo tons in December, and 80,ooa tons--or 12 per cent of the pre- attack level-in March 1945. As for aviation and motor gas- oline, the results were even better. Practically all German aviation gasoline was made by the hydrogenation process in synthetic-oil plants, and those plants were the first to be hit. Aviation gasoline production declined from 170,000 tons per month to 52,000 tons only one month after the oil bomb- ing offensive began, and it had been eliminated completely by the following March.
The effect on Luf twaffe operations was tremendous. Ger- man gasoline stocks had been tight to begin with, and pro- duction losses meant immediate curtailment of consumption. Flight training was steadily shortened, and toward the end of the war pilots were sent into action who had had only forty to forty-five hours in the air. Their inexperience made them easy marks for our highly-trained air crews. Germany's large reserve of military aircraft was grounded with empty
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ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD W AR I1
tanks. Only fighter missions against our bombers were per- mitted, and even those became few and ineffective.
Effectson ground combat were somewhat slower. Use of gasoline was restricted first in motor transport, but in the last stages of the war huge numbers of German tanks were unable to reach the fighting areas, or were abandoned on the battlefields, for lack of fuel. Before the end, wood or coal- burning gas generators, such as had been only moderately successful on buses and trucks, had been put on some fifty tanks.
Chemicals were never singled out as a target, but since most of the chemical industry was closely integrated with synthetic-oil production, attacks on the latter served to dam- age the former as well. When two plants (Leuna and Lud- wigshafen) were shut down as a result of air attacks, Ger- many lost 63 per cent of its synthetic-nitrogen production and 40 per cent of its synthetic-rubber production. Damage to five additional oil plants brought the loss in synthetic nitro- gen to 91 per cent. Nitrogen is essential for all explosives and powder propellants. As early as August 1944, Albert Speer was reporting to Hitler that the attacks on chemicals were threatening Germany's ability to carry on the war. Be- fore V-E Day the Germans were filling their artillery shells with as much as 70 per cent inert rock salt. '
German transportation, including the extensive canal net- work as well as the railways, became a strategic target sys- tem in March 1944, although heavy attacks did not start until September 1944. By the end of October, carloadings were declining rapidly and showing immediate effects in
8U. S. S. B. S. , Ordnance Industry Report (Item #IOI for European War), p. 29; also Oil Division Final Report (Item # ~ o gfor European War), pp. 40-47. Incidentally, the latter item is one of the most illuminating reports in the entire series.
over-all production. By late November and early December all munitions production had been severely affected by the failure to move critical materials.
Even as early as August 1944, the Germans could no longer supply coal to the steel plants of Lorraine and Luxembourg. By February 1945, the Ruhr was just about completely iso- lated. Such coal as was loaded was often confiscated by the railroads for locomotive fuel; even so, by March, locomotives were standing idle for lack of coal in districts where some traffic could otherwise have moved. On March 15, when al- most the whole of the Allied army was still west of the Rhine, Speer reported to Hitler: "The German economy is heading for an inevitable collapse within four to eight weeks. " At that time over-all carloadings were 15 per cent of normal and moving toward zero. '
It was the collapse of transportation which caused the Stra- tegic Bombing Survey to state in one of its most often-quoted passages: "Even if the final military victories that carried the Allied armies across the Rhine and the Oder had not taken place, armaments production would have come to a virtual standstill by May; the German armies, completely bereft of ammunition and of motive power, would almost certainly have had to cease fighting by June or J ~ l y . " ~ But these results of the bombing of Germany came late.
On the credit side, the fact that our ground forces during the last year of the war had little enemy air opposition to con- tend with, while our own planes were making things very rough for the German armies, owed much to our strategic bombing, especially to our bombing of enemy air fields (al-
U. S. S. B. S. , The Eflects of Strategic Bombing on German Transporta- tion (Item #zoo for European War).
6U. S. S. B. S. ,Eflects on German War Economy, p. 14.
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
ways considered good unloading spots for lanes coming home with unused bombs) and to the air battles that attended our bombing forays. Moreover, the shortage of materials, espe- cially oil, which our bombing was imposing on the Germans, did in fact hasten the final collapse of their armies. More important, the Germans in the last year of the war were devoting at least a third of their total war resources to air defense, resources which would otherwise have been avail- able to their armies. We must remember also that some of our attacks, like that on the German V-weapon program, had important defensive results.
Nevertheless, the fact remains that the ultimate destruc- tion of the German armies was practically assured from the time of the successful Allied break-out west of St. Lo late in July 1944, at which time the tangible battlefield results of our strategic bombing, apart from its important contribu- tion to suppressing enemy air activities, added up to very little. By the time those results were making themselves felt seriously, the Battle of the Bulge was a thing of the past and
the Allied armies were well into Germany.
If prior to mid-1943 we had put into our strategic air force
some of the resources used in building up a great army and invasion armada, as some argued we should have done, we would no doubt have got our strategic bombing results faster. However, that is not the same as saying that the war would have ended sooner. The fact is that we did put into strategic bombing a colossal effort. We were also committed to an invasion of France, and there were at the time few grounds for calling that a bad commitment. At the time we made the relevant decisions, our government feared, probably wrongly, that if we limited ourselves to an air and naval effort the
Russians would make a separate peace. If, as is more likely, the Russians had gone on fighting, and if our bombing had guaranteed the success of Soviet ground forces, it would have been their armies and not ours that would have "liberated" western Europe, and that might very well have been there now.
The strategic bombing of Germany during World War I1 was almost totally a new experiment, in which much had to be learned the hard way. We steadily tried to reach out after greater capabilities,especiallyin carrying capacity,depth of penetration, and accuracy of bombing; and we sought, partly and inescapably through trial and error, to find good
target systems. In both respects we can now see many critical and perhaps unnecessary errors which delayed our success. The U. S. A. A. F. paid dearly for the prewar conviction, inherited from Douhet, that fighter escort was unnecessary for bombers like the B-17, unhappily called the "Flying
Fortress. " The disastrous second Schweinfurt raid of October 10, 1943, in which the attacking squadrons lost 30 per cent of their aircraft, indicated that deep daylight penetrations into Germany had to await the availability of large numbers of long-range fighters. Starting in early 1944, the P-51s played a major part in destroying the German Air Force. Similarly, the British paid heavily for their early conviction that night bombing could be precise enough for specific industrial tar-
gets. When that was disproved, they adopted in 1942 Chief of Bomber Command Sir Arthur Harris' compensating con- viction that area bombing was the most promising method of aerial attack anyway, since the search for specific target systems was only a futile search for "panacea targets. " Sir Arthur, incidentally, had not lost that conviction even when
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR 11
he wrote his memoirs after the war's end; nor had some of the senior officers who had served under him. '
The basic strategy for the Combined Bomber Offensive was laid down in the Casablanca Conference of January 1943, where the relevant directive stated the primary objec- tive of the strategic air offensive: "the progressive destruction and dislocation of the German military, industrial, and eco- nomic system, and the undermining of the morale of the German people to a point where their capacity for armed resistance is fatally weakened. " The directive went on to name five primary target systems in the following order: ( I ) sub- marine construction yards, ( 2 ) the aircraft industry, (3) transportation, (4) the oil industry, (5) generalized targets in the enemy war industry. In the absence of specific instruc- tions to the contrary, air force commanders retained the
authority to alter the order of priority for individual raids according to their own judgment.
On June 10, 1943, a new and much more pointed directive from the Combined Chiefs of Staff set down the "Point- blank" target system, and created the so-called "Jockey" Committee as an advisory body on targets; this Committee carried out its function until it merged with the Combined Strategic Targets Committee in September 1944. Under "Pointblank," German fighter plane production and existing strength were made unequivocally top-priority targets for the American bomber forces. The governing considerations were: (a) air dominance had to be established in the face of in- creasing German fighter strength, which threatened the con-
See Marshal of the R. A. F. Sir Arthur Harris, Bomber Offensive,Col- lins, London, 1947, especially pp. 75, 220-234. Sir Arthur's Senior Air Staff Officer (or Chief of Staff), now Air Marshal Sir Robert Saundb~,has espoused the same views in his numerous articles in British professional journals.
tinuance of the bomber offensive; (b) destruction of the German Air Force would provide the best short-term stra- tegic-bombing contribution to the planned invasion of the Continent; and (c) the immediately preceding months, with their brilliant victories at sea, had brought the submarine menace under control and had shown, moreover, that the destruction of submarine yards and bases along with the other desired target systems was simply beyond the capabil- ities of existing bomber forces. The June 1943 directive thus recognized the need for adjusting to limited capabilities by
ordering concentration on a single specifically-designated target system. All other systems were made secondary, and individual force commanders were given minimum dis- cretion with regard to choice among systems to be attacked.
In principle, the selection of the German Air Force as a target system, and especially of its fighter contingent, was right. It placed first things first according to common sense as well as to the well-known Douhet dictum that command of the air must be won before it can be exploited. However, the offensive against the German aircraft industry, which reached its greatest intensity in the period February-April 1944, was a failure. Attacks upon airframe plants simply induced the
Germans to disperse their facilities, which proved relatively easy to do since the tools mainly used were fairly mobile. The temporary loss of production resulting from such move- ment of equipment was about all that could be chalked up to the credit of the attacks.
The fact remains that front-line German fighter air strength increased sharply during the Allied offensiveagainst it. No doubt the increase was less than it would have been but for our bombing. The Aircraft Division of the U. S. S. B. S. estimated that some 18,000 aircraft of all types were denied
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
the German Air Force in the period between July 1943 and December 1944. ~That figure, based on the disparity between planned and actual production, is ventured against an al- leged total production for the same period of 53,000 air- craft-a quite improbable figure. The economists who pre- pared the over-all economic-effectsreport of u. s.
STRATEGIC BOMBING IN WORLD WAR I1
AIRPOWER had a mighty vindication in World War 11. But it was Mitchell's conception of it-"anything that flies"- rather than Douhet's that was vindicated. It was in tactical employment that success was most spectacular and that the air forces won the unqualified respect and admiration of the older services. By contrast, the purely strategic successes, however far-reaching in particular instances, were never completely convincing to uncommitted observers. Against Germany they came too late to have a clearly decisive effect; against Japan they were imposed on an enemy already prostrated by other forms of war. If airmen were like labora- tory animals running a maze, they would seek to repeat
successes and to recoil from frustrations. They would now be all in favor of tactical as against strategic uses of air power. But being instead very human, and knowing also the power
of nuclear weapons, they have remained intensely loyal to ! their original strategic ideas.
The conditions of any future war in which nuclear weap- ons are used will be critically different from those of World War I1 in almost every significant respect. Nevertheless, because the experience of World War I1 is often appealed to as having "proved" this or that about air power, there is value in summarizing that experience briefly and objectively. It is, for all practical purposes, the only experience we have with strategic bombing. Small wonder that it has influenced importantly the ideas we still carry around on the subject,
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
especially with respect to the amount of destruction neces- sary to win a war by strategic bombing.
The Allied strategic bombing campaigns against Germany and Japan in World War I1 are, despite their complexity and magnitude, among the most brilliantly illuminated military campaigns of all time. The United States Strategic Bombing Survey (U. S. S. B. S. ) carried out its survey of Allied bombing in Europe on the heels of the advancing Allied armies, in the hope of applying the resulting lessons to the strategic bombing of Japan. However, the victory over Japan fol- lowed soon thereafter, and the Survey organization pro-
ceeded at once to make a comparable study of the campaign against Japan.
The resulting work comprises 208 separate published items for the European war and 108 items for the Pacific war. The Survey staff was in most fields marked by very high com- petence and talent, and the manner in which the members were selected provided about as good a guarantee against bias as could be found. There were also some complementary studies carried on by other organizations or individuals, some of which benefited from being under less pressure of
time than was imposed on the authors of the Survey. ' Thus,
lThe British work most nearly comparable to the U. S. S. B. S. is that by the British Bombing Survey Unit (called during the war the RAF Bombing Analysis Unit). However, the publications of that organization- most of them classified-have had only the most limited distribution within the United States. The basic volume in the series is entitled The Strategic Air War Against Germany, 1939-45. In America, there have been some distinctive publications (also originally classified) by an agency of the Air Force called the AAF Evaluation Board, which was rather more con- cerned with tactical targets and operations, such as those incident to the Normandy landing, than with strategic air operations. The British Bomb- ing Survey Unit tended to straddle both strategic and tactical operations. It was, unlike the other surveys mentioned, very largely directed by persons who had made heavy commitments to operational decisions. With respect
the relevant facts of any importance are available. All one has to do is read the appropriate publications carefully with an open mind.
The Attack on the German War Economy
With respect to the German campaign, study of the survey findings leads to three major conclusions: (I) our strategic bombing brougnt the German war economy to the point of collapse; (2) that result came very late in the war, too late to develop its full potential effects on the ground and naval campaigns, which were already proceeding to a decisive con- clusion; and (3) given only the air power actually in Allied hands, but assuming better understanding of the capabilities of strategic bombing and especially a wiser choice of targets, the positive results achieved by bombing could have come much sooner than they did. Had they come sooner by six months, their beneficial influence for shortening the war and saving Allied lives would have been unequivocal.
Let us examine the first conclusion. The oft-repeated argu- ment, based on U. S. S. B. S. statistics, that German war produc- tion in almost all categories increased drastically between the middle of 1942 and the middle of 1944, is beside the point, because the scale of bombing which brought about the final significant results had barely begun by mid-1944. The weight
--
to targets within France, one must mention also the work of the French Operational Research Group.
The general, semi-officialhistories which might be studied in conjunction with the abovezited reports are, for the United States, W. F. Craven and J. L. Cate, The Army Air Forces in World War 11, 7 vols. , University of Chicago Press, Chicago, 1948-1955;and for the British, Denis Richards and Hilary St. George Saunders, Royal Air Force, 1939-1945, 3 vols. , H. M. Stationery Office, London, 1953-1954. See also Burton H. Klein, Germany's Economic Preparations For War, Harvard University Press, Cambridge, '959.
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of Allied attack, which in 1942 averaged under 6,000 tons
monthly, rose in 1944 to an average of 131,000 tons monthly-
a more than twenty fold increase. The greategt rate of in- crease occurred just prior to the Normandy invasion, which itself absorbed in tactical operations for many months the major part of our strategic-bombing capabilities. Along with this increase in tonnage of bombs dropped came a great im- provement in operational techniques, especially in the use of radio direction devices. And beginning only in February
1944, large numbers of P-51 long-range fighters became avail- able for escorting bomber sorties practically anywhere within Germany.
Also, until mid-1942 the German war economy contained a large amount of slack. Contrary to general opinion, that economy was far from fully mobilized for war either in the kind of commodities produced or in the rate of production. The labor force was essentially on a single-shift basis and in- cluded relatively few women. The great increases in German war production over the next two years, despite our bomb- ing, resulted mostly from the taking up of this slack. Even so, judged by the standard of British industrial mobilization,
the German economy never attained anything like its full war potential. '
In any case, from our point of view it would not matter whether or not production as a whole diminished if the Germans had been denied even one truly indispensable war commodity, such as liquid fuel. In the final stages of the war, that is just what happened. Allied bombers knocked out the German industries producing liquid fuels and chemicals.
2 See U. S. S. B. S. , The Effects of Strategic Bombing on the German War Economy (Item #3 for European War), especially pp. 6-11. See also Klein, 0p. d.
I n an overlapping campaign they also effectively knocked out the German transportation services, upon which everything else depended.
German oil-production facilities were recommended as a top-priority target on March 5, 1944, and oficially designated as such in a directive of June 8, two days after the Normandy landing. There had meanwhile been two days of attacks on the industry during May, but the full-scale attack started at the end of June and continued until March 1945. There were 555 separate attacks on 135 different targets, including every synthetic-fuelplant and major refinery known to be in oper-
ation.
The beginning of the onslaught started a precipitous drop
in German oil production. From an average of 662,000 tons per month, it went down to 422,000 tons in June, z60,ooo tons in December, and 80,ooa tons--or 12 per cent of the pre- attack level-in March 1945. As for aviation and motor gas- oline, the results were even better. Practically all German aviation gasoline was made by the hydrogenation process in synthetic-oil plants, and those plants were the first to be hit. Aviation gasoline production declined from 170,000 tons per month to 52,000 tons only one month after the oil bomb- ing offensive began, and it had been eliminated completely by the following March.
The effect on Luf twaffe operations was tremendous. Ger- man gasoline stocks had been tight to begin with, and pro- duction losses meant immediate curtailment of consumption. Flight training was steadily shortened, and toward the end of the war pilots were sent into action who had had only forty to forty-five hours in the air. Their inexperience made them easy marks for our highly-trained air crews. Germany's large reserve of military aircraft was grounded with empty
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ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD W AR I1
tanks. Only fighter missions against our bombers were per- mitted, and even those became few and ineffective.
Effectson ground combat were somewhat slower. Use of gasoline was restricted first in motor transport, but in the last stages of the war huge numbers of German tanks were unable to reach the fighting areas, or were abandoned on the battlefields, for lack of fuel. Before the end, wood or coal- burning gas generators, such as had been only moderately successful on buses and trucks, had been put on some fifty tanks.
Chemicals were never singled out as a target, but since most of the chemical industry was closely integrated with synthetic-oil production, attacks on the latter served to dam- age the former as well. When two plants (Leuna and Lud- wigshafen) were shut down as a result of air attacks, Ger- many lost 63 per cent of its synthetic-nitrogen production and 40 per cent of its synthetic-rubber production. Damage to five additional oil plants brought the loss in synthetic nitro- gen to 91 per cent. Nitrogen is essential for all explosives and powder propellants. As early as August 1944, Albert Speer was reporting to Hitler that the attacks on chemicals were threatening Germany's ability to carry on the war. Be- fore V-E Day the Germans were filling their artillery shells with as much as 70 per cent inert rock salt. '
German transportation, including the extensive canal net- work as well as the railways, became a strategic target sys- tem in March 1944, although heavy attacks did not start until September 1944. By the end of October, carloadings were declining rapidly and showing immediate effects in
8U. S. S. B. S. , Ordnance Industry Report (Item #IOI for European War), p. 29; also Oil Division Final Report (Item # ~ o gfor European War), pp. 40-47. Incidentally, the latter item is one of the most illuminating reports in the entire series.
over-all production. By late November and early December all munitions production had been severely affected by the failure to move critical materials.
Even as early as August 1944, the Germans could no longer supply coal to the steel plants of Lorraine and Luxembourg. By February 1945, the Ruhr was just about completely iso- lated. Such coal as was loaded was often confiscated by the railroads for locomotive fuel; even so, by March, locomotives were standing idle for lack of coal in districts where some traffic could otherwise have moved. On March 15, when al- most the whole of the Allied army was still west of the Rhine, Speer reported to Hitler: "The German economy is heading for an inevitable collapse within four to eight weeks. " At that time over-all carloadings were 15 per cent of normal and moving toward zero. '
It was the collapse of transportation which caused the Stra- tegic Bombing Survey to state in one of its most often-quoted passages: "Even if the final military victories that carried the Allied armies across the Rhine and the Oder had not taken place, armaments production would have come to a virtual standstill by May; the German armies, completely bereft of ammunition and of motive power, would almost certainly have had to cease fighting by June or J ~ l y . " ~ But these results of the bombing of Germany came late.
On the credit side, the fact that our ground forces during the last year of the war had little enemy air opposition to con- tend with, while our own planes were making things very rough for the German armies, owed much to our strategic bombing, especially to our bombing of enemy air fields (al-
U. S. S. B. S. , The Eflects of Strategic Bombing on German Transporta- tion (Item #zoo for European War).
6U. S. S. B. S. ,Eflects on German War Economy, p. 14.
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
ways considered good unloading spots for lanes coming home with unused bombs) and to the air battles that attended our bombing forays. Moreover, the shortage of materials, espe- cially oil, which our bombing was imposing on the Germans, did in fact hasten the final collapse of their armies. More important, the Germans in the last year of the war were devoting at least a third of their total war resources to air defense, resources which would otherwise have been avail- able to their armies. We must remember also that some of our attacks, like that on the German V-weapon program, had important defensive results.
Nevertheless, the fact remains that the ultimate destruc- tion of the German armies was practically assured from the time of the successful Allied break-out west of St. Lo late in July 1944, at which time the tangible battlefield results of our strategic bombing, apart from its important contribu- tion to suppressing enemy air activities, added up to very little. By the time those results were making themselves felt seriously, the Battle of the Bulge was a thing of the past and
the Allied armies were well into Germany.
If prior to mid-1943 we had put into our strategic air force
some of the resources used in building up a great army and invasion armada, as some argued we should have done, we would no doubt have got our strategic bombing results faster. However, that is not the same as saying that the war would have ended sooner. The fact is that we did put into strategic bombing a colossal effort. We were also committed to an invasion of France, and there were at the time few grounds for calling that a bad commitment. At the time we made the relevant decisions, our government feared, probably wrongly, that if we limited ourselves to an air and naval effort the
Russians would make a separate peace. If, as is more likely, the Russians had gone on fighting, and if our bombing had guaranteed the success of Soviet ground forces, it would have been their armies and not ours that would have "liberated" western Europe, and that might very well have been there now.
The strategic bombing of Germany during World War I1 was almost totally a new experiment, in which much had to be learned the hard way. We steadily tried to reach out after greater capabilities,especiallyin carrying capacity,depth of penetration, and accuracy of bombing; and we sought, partly and inescapably through trial and error, to find good
target systems. In both respects we can now see many critical and perhaps unnecessary errors which delayed our success. The U. S. A. A. F. paid dearly for the prewar conviction, inherited from Douhet, that fighter escort was unnecessary for bombers like the B-17, unhappily called the "Flying
Fortress. " The disastrous second Schweinfurt raid of October 10, 1943, in which the attacking squadrons lost 30 per cent of their aircraft, indicated that deep daylight penetrations into Germany had to await the availability of large numbers of long-range fighters. Starting in early 1944, the P-51s played a major part in destroying the German Air Force. Similarly, the British paid heavily for their early conviction that night bombing could be precise enough for specific industrial tar-
gets. When that was disproved, they adopted in 1942 Chief of Bomber Command Sir Arthur Harris' compensating con- viction that area bombing was the most promising method of aerial attack anyway, since the search for specific target systems was only a futile search for "panacea targets. " Sir Arthur, incidentally, had not lost that conviction even when
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR 11
he wrote his memoirs after the war's end; nor had some of the senior officers who had served under him. '
The basic strategy for the Combined Bomber Offensive was laid down in the Casablanca Conference of January 1943, where the relevant directive stated the primary objec- tive of the strategic air offensive: "the progressive destruction and dislocation of the German military, industrial, and eco- nomic system, and the undermining of the morale of the German people to a point where their capacity for armed resistance is fatally weakened. " The directive went on to name five primary target systems in the following order: ( I ) sub- marine construction yards, ( 2 ) the aircraft industry, (3) transportation, (4) the oil industry, (5) generalized targets in the enemy war industry. In the absence of specific instruc- tions to the contrary, air force commanders retained the
authority to alter the order of priority for individual raids according to their own judgment.
On June 10, 1943, a new and much more pointed directive from the Combined Chiefs of Staff set down the "Point- blank" target system, and created the so-called "Jockey" Committee as an advisory body on targets; this Committee carried out its function until it merged with the Combined Strategic Targets Committee in September 1944. Under "Pointblank," German fighter plane production and existing strength were made unequivocally top-priority targets for the American bomber forces. The governing considerations were: (a) air dominance had to be established in the face of in- creasing German fighter strength, which threatened the con-
See Marshal of the R. A. F. Sir Arthur Harris, Bomber Offensive,Col- lins, London, 1947, especially pp. 75, 220-234. Sir Arthur's Senior Air Staff Officer (or Chief of Staff), now Air Marshal Sir Robert Saundb~,has espoused the same views in his numerous articles in British professional journals.
tinuance of the bomber offensive; (b) destruction of the German Air Force would provide the best short-term stra- tegic-bombing contribution to the planned invasion of the Continent; and (c) the immediately preceding months, with their brilliant victories at sea, had brought the submarine menace under control and had shown, moreover, that the destruction of submarine yards and bases along with the other desired target systems was simply beyond the capabil- ities of existing bomber forces. The June 1943 directive thus recognized the need for adjusting to limited capabilities by
ordering concentration on a single specifically-designated target system. All other systems were made secondary, and individual force commanders were given minimum dis- cretion with regard to choice among systems to be attacked.
In principle, the selection of the German Air Force as a target system, and especially of its fighter contingent, was right. It placed first things first according to common sense as well as to the well-known Douhet dictum that command of the air must be won before it can be exploited. However, the offensive against the German aircraft industry, which reached its greatest intensity in the period February-April 1944, was a failure. Attacks upon airframe plants simply induced the
Germans to disperse their facilities, which proved relatively easy to do since the tools mainly used were fairly mobile. The temporary loss of production resulting from such move- ment of equipment was about all that could be chalked up to the credit of the attacks.
The fact remains that front-line German fighter air strength increased sharply during the Allied offensiveagainst it. No doubt the increase was less than it would have been but for our bombing. The Aircraft Division of the U. S. S. B. S. estimated that some 18,000 aircraft of all types were denied
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
the German Air Force in the period between July 1943 and December 1944. ~That figure, based on the disparity between planned and actual production, is ventured against an al- leged total production for the same period of 53,000 air- craft-a quite improbable figure. The economists who pre- pared the over-all economic-effectsreport of u. s. S. B.
AIRPOWER had a mighty vindication in World War 11. But it was Mitchell's conception of it-"anything that flies"- rather than Douhet's that was vindicated. It was in tactical employment that success was most spectacular and that the air forces won the unqualified respect and admiration of the older services. By contrast, the purely strategic successes, however far-reaching in particular instances, were never completely convincing to uncommitted observers. Against Germany they came too late to have a clearly decisive effect; against Japan they were imposed on an enemy already prostrated by other forms of war. If airmen were like labora- tory animals running a maze, they would seek to repeat
successes and to recoil from frustrations. They would now be all in favor of tactical as against strategic uses of air power. But being instead very human, and knowing also the power
of nuclear weapons, they have remained intensely loyal to ! their original strategic ideas.
The conditions of any future war in which nuclear weap- ons are used will be critically different from those of World War I1 in almost every significant respect. Nevertheless, because the experience of World War I1 is often appealed to as having "proved" this or that about air power, there is value in summarizing that experience briefly and objectively. It is, for all practical purposes, the only experience we have with strategic bombing. Small wonder that it has influenced importantly the ideas we still carry around on the subject,
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
especially with respect to the amount of destruction neces- sary to win a war by strategic bombing.
The Allied strategic bombing campaigns against Germany and Japan in World War I1 are, despite their complexity and magnitude, among the most brilliantly illuminated military campaigns of all time. The United States Strategic Bombing Survey (U. S. S. B. S. ) carried out its survey of Allied bombing in Europe on the heels of the advancing Allied armies, in the hope of applying the resulting lessons to the strategic bombing of Japan. However, the victory over Japan fol- lowed soon thereafter, and the Survey organization pro-
ceeded at once to make a comparable study of the campaign against Japan.
The resulting work comprises 208 separate published items for the European war and 108 items for the Pacific war. The Survey staff was in most fields marked by very high com- petence and talent, and the manner in which the members were selected provided about as good a guarantee against bias as could be found. There were also some complementary studies carried on by other organizations or individuals, some of which benefited from being under less pressure of
time than was imposed on the authors of the Survey. ' Thus,
lThe British work most nearly comparable to the U. S. S. B. S. is that by the British Bombing Survey Unit (called during the war the RAF Bombing Analysis Unit). However, the publications of that organization- most of them classified-have had only the most limited distribution within the United States. The basic volume in the series is entitled The Strategic Air War Against Germany, 1939-45. In America, there have been some distinctive publications (also originally classified) by an agency of the Air Force called the AAF Evaluation Board, which was rather more con- cerned with tactical targets and operations, such as those incident to the Normandy landing, than with strategic air operations. The British Bomb- ing Survey Unit tended to straddle both strategic and tactical operations. It was, unlike the other surveys mentioned, very largely directed by persons who had made heavy commitments to operational decisions. With respect
the relevant facts of any importance are available. All one has to do is read the appropriate publications carefully with an open mind.
The Attack on the German War Economy
With respect to the German campaign, study of the survey findings leads to three major conclusions: (I) our strategic bombing brougnt the German war economy to the point of collapse; (2) that result came very late in the war, too late to develop its full potential effects on the ground and naval campaigns, which were already proceeding to a decisive con- clusion; and (3) given only the air power actually in Allied hands, but assuming better understanding of the capabilities of strategic bombing and especially a wiser choice of targets, the positive results achieved by bombing could have come much sooner than they did. Had they come sooner by six months, their beneficial influence for shortening the war and saving Allied lives would have been unequivocal.
Let us examine the first conclusion. The oft-repeated argu- ment, based on U. S. S. B. S. statistics, that German war produc- tion in almost all categories increased drastically between the middle of 1942 and the middle of 1944, is beside the point, because the scale of bombing which brought about the final significant results had barely begun by mid-1944. The weight
--
to targets within France, one must mention also the work of the French Operational Research Group.
The general, semi-officialhistories which might be studied in conjunction with the abovezited reports are, for the United States, W. F. Craven and J. L. Cate, The Army Air Forces in World War 11, 7 vols. , University of Chicago Press, Chicago, 1948-1955;and for the British, Denis Richards and Hilary St. George Saunders, Royal Air Force, 1939-1945, 3 vols. , H. M. Stationery Office, London, 1953-1954. See also Burton H. Klein, Germany's Economic Preparations For War, Harvard University Press, Cambridge, '959.
? ~ I
I
I
I
I
I
of Allied attack, which in 1942 averaged under 6,000 tons
monthly, rose in 1944 to an average of 131,000 tons monthly-
a more than twenty fold increase. The greategt rate of in- crease occurred just prior to the Normandy invasion, which itself absorbed in tactical operations for many months the major part of our strategic-bombing capabilities. Along with this increase in tonnage of bombs dropped came a great im- provement in operational techniques, especially in the use of radio direction devices. And beginning only in February
1944, large numbers of P-51 long-range fighters became avail- able for escorting bomber sorties practically anywhere within Germany.
Also, until mid-1942 the German war economy contained a large amount of slack. Contrary to general opinion, that economy was far from fully mobilized for war either in the kind of commodities produced or in the rate of production. The labor force was essentially on a single-shift basis and in- cluded relatively few women. The great increases in German war production over the next two years, despite our bomb- ing, resulted mostly from the taking up of this slack. Even so, judged by the standard of British industrial mobilization,
the German economy never attained anything like its full war potential. '
In any case, from our point of view it would not matter whether or not production as a whole diminished if the Germans had been denied even one truly indispensable war commodity, such as liquid fuel. In the final stages of the war, that is just what happened. Allied bombers knocked out the German industries producing liquid fuels and chemicals.
2 See U. S. S. B. S. , The Effects of Strategic Bombing on the German War Economy (Item #3 for European War), especially pp. 6-11. See also Klein, 0p. d.
I n an overlapping campaign they also effectively knocked out the German transportation services, upon which everything else depended.
German oil-production facilities were recommended as a top-priority target on March 5, 1944, and oficially designated as such in a directive of June 8, two days after the Normandy landing. There had meanwhile been two days of attacks on the industry during May, but the full-scale attack started at the end of June and continued until March 1945. There were 555 separate attacks on 135 different targets, including every synthetic-fuelplant and major refinery known to be in oper-
ation.
The beginning of the onslaught started a precipitous drop
in German oil production. From an average of 662,000 tons per month, it went down to 422,000 tons in June, z60,ooo tons in December, and 80,ooa tons--or 12 per cent of the pre- attack level-in March 1945. As for aviation and motor gas- oline, the results were even better. Practically all German aviation gasoline was made by the hydrogenation process in synthetic-oil plants, and those plants were the first to be hit. Aviation gasoline production declined from 170,000 tons per month to 52,000 tons only one month after the oil bomb- ing offensive began, and it had been eliminated completely by the following March.
The effect on Luf twaffe operations was tremendous. Ger- man gasoline stocks had been tight to begin with, and pro- duction losses meant immediate curtailment of consumption. Flight training was steadily shortened, and toward the end of the war pilots were sent into action who had had only forty to forty-five hours in the air. Their inexperience made them easy marks for our highly-trained air crews. Germany's large reserve of military aircraft was grounded with empty
I
~ I
'
-
I
ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD W AR I1
tanks. Only fighter missions against our bombers were per- mitted, and even those became few and ineffective.
Effectson ground combat were somewhat slower. Use of gasoline was restricted first in motor transport, but in the last stages of the war huge numbers of German tanks were unable to reach the fighting areas, or were abandoned on the battlefields, for lack of fuel. Before the end, wood or coal- burning gas generators, such as had been only moderately successful on buses and trucks, had been put on some fifty tanks.
Chemicals were never singled out as a target, but since most of the chemical industry was closely integrated with synthetic-oil production, attacks on the latter served to dam- age the former as well. When two plants (Leuna and Lud- wigshafen) were shut down as a result of air attacks, Ger- many lost 63 per cent of its synthetic-nitrogen production and 40 per cent of its synthetic-rubber production. Damage to five additional oil plants brought the loss in synthetic nitro- gen to 91 per cent. Nitrogen is essential for all explosives and powder propellants. As early as August 1944, Albert Speer was reporting to Hitler that the attacks on chemicals were threatening Germany's ability to carry on the war. Be- fore V-E Day the Germans were filling their artillery shells with as much as 70 per cent inert rock salt. '
German transportation, including the extensive canal net- work as well as the railways, became a strategic target sys- tem in March 1944, although heavy attacks did not start until September 1944. By the end of October, carloadings were declining rapidly and showing immediate effects in
8U. S. S. B. S. , Ordnance Industry Report (Item #IOI for European War), p. 29; also Oil Division Final Report (Item # ~ o gfor European War), pp. 40-47. Incidentally, the latter item is one of the most illuminating reports in the entire series.
over-all production. By late November and early December all munitions production had been severely affected by the failure to move critical materials.
Even as early as August 1944, the Germans could no longer supply coal to the steel plants of Lorraine and Luxembourg. By February 1945, the Ruhr was just about completely iso- lated. Such coal as was loaded was often confiscated by the railroads for locomotive fuel; even so, by March, locomotives were standing idle for lack of coal in districts where some traffic could otherwise have moved. On March 15, when al- most the whole of the Allied army was still west of the Rhine, Speer reported to Hitler: "The German economy is heading for an inevitable collapse within four to eight weeks. " At that time over-all carloadings were 15 per cent of normal and moving toward zero. '
It was the collapse of transportation which caused the Stra- tegic Bombing Survey to state in one of its most often-quoted passages: "Even if the final military victories that carried the Allied armies across the Rhine and the Oder had not taken place, armaments production would have come to a virtual standstill by May; the German armies, completely bereft of ammunition and of motive power, would almost certainly have had to cease fighting by June or J ~ l y . " ~ But these results of the bombing of Germany came late.
On the credit side, the fact that our ground forces during the last year of the war had little enemy air opposition to con- tend with, while our own planes were making things very rough for the German armies, owed much to our strategic bombing, especially to our bombing of enemy air fields (al-
U. S. S. B. S. , The Eflects of Strategic Bombing on German Transporta- tion (Item #zoo for European War).
6U. S. S. B. S. ,Eflects on German War Economy, p. 14.
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
ways considered good unloading spots for lanes coming home with unused bombs) and to the air battles that attended our bombing forays. Moreover, the shortage of materials, espe- cially oil, which our bombing was imposing on the Germans, did in fact hasten the final collapse of their armies. More important, the Germans in the last year of the war were devoting at least a third of their total war resources to air defense, resources which would otherwise have been avail- able to their armies. We must remember also that some of our attacks, like that on the German V-weapon program, had important defensive results.
Nevertheless, the fact remains that the ultimate destruc- tion of the German armies was practically assured from the time of the successful Allied break-out west of St. Lo late in July 1944, at which time the tangible battlefield results of our strategic bombing, apart from its important contribu- tion to suppressing enemy air activities, added up to very little. By the time those results were making themselves felt seriously, the Battle of the Bulge was a thing of the past and
the Allied armies were well into Germany.
If prior to mid-1943 we had put into our strategic air force
some of the resources used in building up a great army and invasion armada, as some argued we should have done, we would no doubt have got our strategic bombing results faster. However, that is not the same as saying that the war would have ended sooner. The fact is that we did put into strategic bombing a colossal effort. We were also committed to an invasion of France, and there were at the time few grounds for calling that a bad commitment. At the time we made the relevant decisions, our government feared, probably wrongly, that if we limited ourselves to an air and naval effort the
Russians would make a separate peace. If, as is more likely, the Russians had gone on fighting, and if our bombing had guaranteed the success of Soviet ground forces, it would have been their armies and not ours that would have "liberated" western Europe, and that might very well have been there now.
The strategic bombing of Germany during World War I1 was almost totally a new experiment, in which much had to be learned the hard way. We steadily tried to reach out after greater capabilities,especiallyin carrying capacity,depth of penetration, and accuracy of bombing; and we sought, partly and inescapably through trial and error, to find good
target systems. In both respects we can now see many critical and perhaps unnecessary errors which delayed our success. The U. S. A. A. F. paid dearly for the prewar conviction, inherited from Douhet, that fighter escort was unnecessary for bombers like the B-17, unhappily called the "Flying
Fortress. " The disastrous second Schweinfurt raid of October 10, 1943, in which the attacking squadrons lost 30 per cent of their aircraft, indicated that deep daylight penetrations into Germany had to await the availability of large numbers of long-range fighters. Starting in early 1944, the P-51s played a major part in destroying the German Air Force. Similarly, the British paid heavily for their early conviction that night bombing could be precise enough for specific industrial tar-
gets. When that was disproved, they adopted in 1942 Chief of Bomber Command Sir Arthur Harris' compensating con- viction that area bombing was the most promising method of aerial attack anyway, since the search for specific target systems was only a futile search for "panacea targets. " Sir Arthur, incidentally, had not lost that conviction even when
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR 11
he wrote his memoirs after the war's end; nor had some of the senior officers who had served under him. '
The basic strategy for the Combined Bomber Offensive was laid down in the Casablanca Conference of January 1943, where the relevant directive stated the primary objec- tive of the strategic air offensive: "the progressive destruction and dislocation of the German military, industrial, and eco- nomic system, and the undermining of the morale of the German people to a point where their capacity for armed resistance is fatally weakened. " The directive went on to name five primary target systems in the following order: ( I ) sub- marine construction yards, ( 2 ) the aircraft industry, (3) transportation, (4) the oil industry, (5) generalized targets in the enemy war industry. In the absence of specific instruc- tions to the contrary, air force commanders retained the
authority to alter the order of priority for individual raids according to their own judgment.
On June 10, 1943, a new and much more pointed directive from the Combined Chiefs of Staff set down the "Point- blank" target system, and created the so-called "Jockey" Committee as an advisory body on targets; this Committee carried out its function until it merged with the Combined Strategic Targets Committee in September 1944. Under "Pointblank," German fighter plane production and existing strength were made unequivocally top-priority targets for the American bomber forces. The governing considerations were: (a) air dominance had to be established in the face of in- creasing German fighter strength, which threatened the con-
See Marshal of the R. A. F. Sir Arthur Harris, Bomber Offensive,Col- lins, London, 1947, especially pp. 75, 220-234. Sir Arthur's Senior Air Staff Officer (or Chief of Staff), now Air Marshal Sir Robert Saundb~,has espoused the same views in his numerous articles in British professional journals.
tinuance of the bomber offensive; (b) destruction of the German Air Force would provide the best short-term stra- tegic-bombing contribution to the planned invasion of the Continent; and (c) the immediately preceding months, with their brilliant victories at sea, had brought the submarine menace under control and had shown, moreover, that the destruction of submarine yards and bases along with the other desired target systems was simply beyond the capabil- ities of existing bomber forces. The June 1943 directive thus recognized the need for adjusting to limited capabilities by
ordering concentration on a single specifically-designated target system. All other systems were made secondary, and individual force commanders were given minimum dis- cretion with regard to choice among systems to be attacked.
In principle, the selection of the German Air Force as a target system, and especially of its fighter contingent, was right. It placed first things first according to common sense as well as to the well-known Douhet dictum that command of the air must be won before it can be exploited. However, the offensive against the German aircraft industry, which reached its greatest intensity in the period February-April 1944, was a failure. Attacks upon airframe plants simply induced the
Germans to disperse their facilities, which proved relatively easy to do since the tools mainly used were fairly mobile. The temporary loss of production resulting from such move- ment of equipment was about all that could be chalked up to the credit of the attacks.
The fact remains that front-line German fighter air strength increased sharply during the Allied offensiveagainst it. No doubt the increase was less than it would have been but for our bombing. The Aircraft Division of the U. S. S. B. S. estimated that some 18,000 aircraft of all types were denied
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
the German Air Force in the period between July 1943 and December 1944. ~That figure, based on the disparity between planned and actual production, is ventured against an al- leged total production for the same period of 53,000 air- craft-a quite improbable figure. The economists who pre- pared the over-all economic-effectsreport of u. s.
STRATEGIC BOMBING IN WORLD WAR I1
AIRPOWER had a mighty vindication in World War 11. But it was Mitchell's conception of it-"anything that flies"- rather than Douhet's that was vindicated. It was in tactical employment that success was most spectacular and that the air forces won the unqualified respect and admiration of the older services. By contrast, the purely strategic successes, however far-reaching in particular instances, were never completely convincing to uncommitted observers. Against Germany they came too late to have a clearly decisive effect; against Japan they were imposed on an enemy already prostrated by other forms of war. If airmen were like labora- tory animals running a maze, they would seek to repeat
successes and to recoil from frustrations. They would now be all in favor of tactical as against strategic uses of air power. But being instead very human, and knowing also the power
of nuclear weapons, they have remained intensely loyal to ! their original strategic ideas.
The conditions of any future war in which nuclear weap- ons are used will be critically different from those of World War I1 in almost every significant respect. Nevertheless, because the experience of World War I1 is often appealed to as having "proved" this or that about air power, there is value in summarizing that experience briefly and objectively. It is, for all practical purposes, the only experience we have with strategic bombing. Small wonder that it has influenced importantly the ideas we still carry around on the subject,
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
especially with respect to the amount of destruction neces- sary to win a war by strategic bombing.
The Allied strategic bombing campaigns against Germany and Japan in World War I1 are, despite their complexity and magnitude, among the most brilliantly illuminated military campaigns of all time. The United States Strategic Bombing Survey (U. S. S. B. S. ) carried out its survey of Allied bombing in Europe on the heels of the advancing Allied armies, in the hope of applying the resulting lessons to the strategic bombing of Japan. However, the victory over Japan fol- lowed soon thereafter, and the Survey organization pro-
ceeded at once to make a comparable study of the campaign against Japan.
The resulting work comprises 208 separate published items for the European war and 108 items for the Pacific war. The Survey staff was in most fields marked by very high com- petence and talent, and the manner in which the members were selected provided about as good a guarantee against bias as could be found. There were also some complementary studies carried on by other organizations or individuals, some of which benefited from being under less pressure of
time than was imposed on the authors of the Survey. ' Thus,
lThe British work most nearly comparable to the U. S. S. B. S. is that by the British Bombing Survey Unit (called during the war the RAF Bombing Analysis Unit). However, the publications of that organization- most of them classified-have had only the most limited distribution within the United States. The basic volume in the series is entitled The Strategic Air War Against Germany, 1939-45. In America, there have been some distinctive publications (also originally classified) by an agency of the Air Force called the AAF Evaluation Board, which was rather more con- cerned with tactical targets and operations, such as those incident to the Normandy landing, than with strategic air operations. The British Bomb- ing Survey Unit tended to straddle both strategic and tactical operations. It was, unlike the other surveys mentioned, very largely directed by persons who had made heavy commitments to operational decisions. With respect
the relevant facts of any importance are available. All one has to do is read the appropriate publications carefully with an open mind.
The Attack on the German War Economy
With respect to the German campaign, study of the survey findings leads to three major conclusions: (I) our strategic bombing brougnt the German war economy to the point of collapse; (2) that result came very late in the war, too late to develop its full potential effects on the ground and naval campaigns, which were already proceeding to a decisive con- clusion; and (3) given only the air power actually in Allied hands, but assuming better understanding of the capabilities of strategic bombing and especially a wiser choice of targets, the positive results achieved by bombing could have come much sooner than they did. Had they come sooner by six months, their beneficial influence for shortening the war and saving Allied lives would have been unequivocal.
Let us examine the first conclusion. The oft-repeated argu- ment, based on U. S. S. B. S. statistics, that German war produc- tion in almost all categories increased drastically between the middle of 1942 and the middle of 1944, is beside the point, because the scale of bombing which brought about the final significant results had barely begun by mid-1944. The weight
--
to targets within France, one must mention also the work of the French Operational Research Group.
The general, semi-officialhistories which might be studied in conjunction with the abovezited reports are, for the United States, W. F. Craven and J. L. Cate, The Army Air Forces in World War 11, 7 vols. , University of Chicago Press, Chicago, 1948-1955;and for the British, Denis Richards and Hilary St. George Saunders, Royal Air Force, 1939-1945, 3 vols. , H. M. Stationery Office, London, 1953-1954. See also Burton H. Klein, Germany's Economic Preparations For War, Harvard University Press, Cambridge, '959.
? ~ I
I
I
I
I
I
of Allied attack, which in 1942 averaged under 6,000 tons
monthly, rose in 1944 to an average of 131,000 tons monthly-
a more than twenty fold increase. The greategt rate of in- crease occurred just prior to the Normandy invasion, which itself absorbed in tactical operations for many months the major part of our strategic-bombing capabilities. Along with this increase in tonnage of bombs dropped came a great im- provement in operational techniques, especially in the use of radio direction devices. And beginning only in February
1944, large numbers of P-51 long-range fighters became avail- able for escorting bomber sorties practically anywhere within Germany.
Also, until mid-1942 the German war economy contained a large amount of slack. Contrary to general opinion, that economy was far from fully mobilized for war either in the kind of commodities produced or in the rate of production. The labor force was essentially on a single-shift basis and in- cluded relatively few women. The great increases in German war production over the next two years, despite our bomb- ing, resulted mostly from the taking up of this slack. Even so, judged by the standard of British industrial mobilization,
the German economy never attained anything like its full war potential. '
In any case, from our point of view it would not matter whether or not production as a whole diminished if the Germans had been denied even one truly indispensable war commodity, such as liquid fuel. In the final stages of the war, that is just what happened. Allied bombers knocked out the German industries producing liquid fuels and chemicals.
2 See U. S. S. B. S. , The Effects of Strategic Bombing on the German War Economy (Item #3 for European War), especially pp. 6-11. See also Klein, 0p. d.
I n an overlapping campaign they also effectively knocked out the German transportation services, upon which everything else depended.
German oil-production facilities were recommended as a top-priority target on March 5, 1944, and oficially designated as such in a directive of June 8, two days after the Normandy landing. There had meanwhile been two days of attacks on the industry during May, but the full-scale attack started at the end of June and continued until March 1945. There were 555 separate attacks on 135 different targets, including every synthetic-fuelplant and major refinery known to be in oper-
ation.
The beginning of the onslaught started a precipitous drop
in German oil production. From an average of 662,000 tons per month, it went down to 422,000 tons in June, z60,ooo tons in December, and 80,ooa tons--or 12 per cent of the pre- attack level-in March 1945. As for aviation and motor gas- oline, the results were even better. Practically all German aviation gasoline was made by the hydrogenation process in synthetic-oil plants, and those plants were the first to be hit. Aviation gasoline production declined from 170,000 tons per month to 52,000 tons only one month after the oil bomb- ing offensive began, and it had been eliminated completely by the following March.
The effect on Luf twaffe operations was tremendous. Ger- man gasoline stocks had been tight to begin with, and pro- duction losses meant immediate curtailment of consumption. Flight training was steadily shortened, and toward the end of the war pilots were sent into action who had had only forty to forty-five hours in the air. Their inexperience made them easy marks for our highly-trained air crews. Germany's large reserve of military aircraft was grounded with empty
I
~ I
'
-
I
ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD W AR I1
tanks. Only fighter missions against our bombers were per- mitted, and even those became few and ineffective.
Effectson ground combat were somewhat slower. Use of gasoline was restricted first in motor transport, but in the last stages of the war huge numbers of German tanks were unable to reach the fighting areas, or were abandoned on the battlefields, for lack of fuel. Before the end, wood or coal- burning gas generators, such as had been only moderately successful on buses and trucks, had been put on some fifty tanks.
Chemicals were never singled out as a target, but since most of the chemical industry was closely integrated with synthetic-oil production, attacks on the latter served to dam- age the former as well. When two plants (Leuna and Lud- wigshafen) were shut down as a result of air attacks, Ger- many lost 63 per cent of its synthetic-nitrogen production and 40 per cent of its synthetic-rubber production. Damage to five additional oil plants brought the loss in synthetic nitro- gen to 91 per cent. Nitrogen is essential for all explosives and powder propellants. As early as August 1944, Albert Speer was reporting to Hitler that the attacks on chemicals were threatening Germany's ability to carry on the war. Be- fore V-E Day the Germans were filling their artillery shells with as much as 70 per cent inert rock salt. '
German transportation, including the extensive canal net- work as well as the railways, became a strategic target sys- tem in March 1944, although heavy attacks did not start until September 1944. By the end of October, carloadings were declining rapidly and showing immediate effects in
8U. S. S. B. S. , Ordnance Industry Report (Item #IOI for European War), p. 29; also Oil Division Final Report (Item # ~ o gfor European War), pp. 40-47. Incidentally, the latter item is one of the most illuminating reports in the entire series.
over-all production. By late November and early December all munitions production had been severely affected by the failure to move critical materials.
Even as early as August 1944, the Germans could no longer supply coal to the steel plants of Lorraine and Luxembourg. By February 1945, the Ruhr was just about completely iso- lated. Such coal as was loaded was often confiscated by the railroads for locomotive fuel; even so, by March, locomotives were standing idle for lack of coal in districts where some traffic could otherwise have moved. On March 15, when al- most the whole of the Allied army was still west of the Rhine, Speer reported to Hitler: "The German economy is heading for an inevitable collapse within four to eight weeks. " At that time over-all carloadings were 15 per cent of normal and moving toward zero. '
It was the collapse of transportation which caused the Stra- tegic Bombing Survey to state in one of its most often-quoted passages: "Even if the final military victories that carried the Allied armies across the Rhine and the Oder had not taken place, armaments production would have come to a virtual standstill by May; the German armies, completely bereft of ammunition and of motive power, would almost certainly have had to cease fighting by June or J ~ l y . " ~ But these results of the bombing of Germany came late.
On the credit side, the fact that our ground forces during the last year of the war had little enemy air opposition to con- tend with, while our own planes were making things very rough for the German armies, owed much to our strategic bombing, especially to our bombing of enemy air fields (al-
U. S. S. B. S. , The Eflects of Strategic Bombing on German Transporta- tion (Item #zoo for European War).
6U. S. S. B. S. ,Eflects on German War Economy, p. 14.
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
ways considered good unloading spots for lanes coming home with unused bombs) and to the air battles that attended our bombing forays. Moreover, the shortage of materials, espe- cially oil, which our bombing was imposing on the Germans, did in fact hasten the final collapse of their armies. More important, the Germans in the last year of the war were devoting at least a third of their total war resources to air defense, resources which would otherwise have been avail- able to their armies. We must remember also that some of our attacks, like that on the German V-weapon program, had important defensive results.
Nevertheless, the fact remains that the ultimate destruc- tion of the German armies was practically assured from the time of the successful Allied break-out west of St. Lo late in July 1944, at which time the tangible battlefield results of our strategic bombing, apart from its important contribu- tion to suppressing enemy air activities, added up to very little. By the time those results were making themselves felt seriously, the Battle of the Bulge was a thing of the past and
the Allied armies were well into Germany.
If prior to mid-1943 we had put into our strategic air force
some of the resources used in building up a great army and invasion armada, as some argued we should have done, we would no doubt have got our strategic bombing results faster. However, that is not the same as saying that the war would have ended sooner. The fact is that we did put into strategic bombing a colossal effort. We were also committed to an invasion of France, and there were at the time few grounds for calling that a bad commitment. At the time we made the relevant decisions, our government feared, probably wrongly, that if we limited ourselves to an air and naval effort the
Russians would make a separate peace. If, as is more likely, the Russians had gone on fighting, and if our bombing had guaranteed the success of Soviet ground forces, it would have been their armies and not ours that would have "liberated" western Europe, and that might very well have been there now.
The strategic bombing of Germany during World War I1 was almost totally a new experiment, in which much had to be learned the hard way. We steadily tried to reach out after greater capabilities,especiallyin carrying capacity,depth of penetration, and accuracy of bombing; and we sought, partly and inescapably through trial and error, to find good
target systems. In both respects we can now see many critical and perhaps unnecessary errors which delayed our success. The U. S. A. A. F. paid dearly for the prewar conviction, inherited from Douhet, that fighter escort was unnecessary for bombers like the B-17, unhappily called the "Flying
Fortress. " The disastrous second Schweinfurt raid of October 10, 1943, in which the attacking squadrons lost 30 per cent of their aircraft, indicated that deep daylight penetrations into Germany had to await the availability of large numbers of long-range fighters. Starting in early 1944, the P-51s played a major part in destroying the German Air Force. Similarly, the British paid heavily for their early conviction that night bombing could be precise enough for specific industrial tar-
gets. When that was disproved, they adopted in 1942 Chief of Bomber Command Sir Arthur Harris' compensating con- viction that area bombing was the most promising method of aerial attack anyway, since the search for specific target systems was only a futile search for "panacea targets. " Sir Arthur, incidentally, had not lost that conviction even when
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR 11
he wrote his memoirs after the war's end; nor had some of the senior officers who had served under him. '
The basic strategy for the Combined Bomber Offensive was laid down in the Casablanca Conference of January 1943, where the relevant directive stated the primary objec- tive of the strategic air offensive: "the progressive destruction and dislocation of the German military, industrial, and eco- nomic system, and the undermining of the morale of the German people to a point where their capacity for armed resistance is fatally weakened. " The directive went on to name five primary target systems in the following order: ( I ) sub- marine construction yards, ( 2 ) the aircraft industry, (3) transportation, (4) the oil industry, (5) generalized targets in the enemy war industry. In the absence of specific instruc- tions to the contrary, air force commanders retained the
authority to alter the order of priority for individual raids according to their own judgment.
On June 10, 1943, a new and much more pointed directive from the Combined Chiefs of Staff set down the "Point- blank" target system, and created the so-called "Jockey" Committee as an advisory body on targets; this Committee carried out its function until it merged with the Combined Strategic Targets Committee in September 1944. Under "Pointblank," German fighter plane production and existing strength were made unequivocally top-priority targets for the American bomber forces. The governing considerations were: (a) air dominance had to be established in the face of in- creasing German fighter strength, which threatened the con-
See Marshal of the R. A. F. Sir Arthur Harris, Bomber Offensive,Col- lins, London, 1947, especially pp. 75, 220-234. Sir Arthur's Senior Air Staff Officer (or Chief of Staff), now Air Marshal Sir Robert Saundb~,has espoused the same views in his numerous articles in British professional journals.
tinuance of the bomber offensive; (b) destruction of the German Air Force would provide the best short-term stra- tegic-bombing contribution to the planned invasion of the Continent; and (c) the immediately preceding months, with their brilliant victories at sea, had brought the submarine menace under control and had shown, moreover, that the destruction of submarine yards and bases along with the other desired target systems was simply beyond the capabil- ities of existing bomber forces. The June 1943 directive thus recognized the need for adjusting to limited capabilities by
ordering concentration on a single specifically-designated target system. All other systems were made secondary, and individual force commanders were given minimum dis- cretion with regard to choice among systems to be attacked.
In principle, the selection of the German Air Force as a target system, and especially of its fighter contingent, was right. It placed first things first according to common sense as well as to the well-known Douhet dictum that command of the air must be won before it can be exploited. However, the offensive against the German aircraft industry, which reached its greatest intensity in the period February-April 1944, was a failure. Attacks upon airframe plants simply induced the
Germans to disperse their facilities, which proved relatively easy to do since the tools mainly used were fairly mobile. The temporary loss of production resulting from such move- ment of equipment was about all that could be chalked up to the credit of the attacks.
The fact remains that front-line German fighter air strength increased sharply during the Allied offensiveagainst it. No doubt the increase was less than it would have been but for our bombing. The Aircraft Division of the U. S. S. B. S. estimated that some 18,000 aircraft of all types were denied
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
the German Air Force in the period between July 1943 and December 1944. ~That figure, based on the disparity between planned and actual production, is ventured against an al- leged total production for the same period of 53,000 air- craft-a quite improbable figure. The economists who pre- pared the over-all economic-effectsreport of u. s. S. B.
