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.
See Marshal of the R.
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,
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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
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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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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.
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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
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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
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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.
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
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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. S. were more cautious, offering the opinion that "it is possible that production would have been 15-20per cent higher in the ab- sence of bombing. "'
In short, the attack on airframe production paid dividends -any diminution of enemy strength is a dividend-but they were not in the category of "decisive. " They did not bear out what had been promised for a concentrated offensiveby air forces of the size we were operating in early 1944. Moreover, we do not know how effectively the German Air Force could have used those "lost" aircraft, in view of shortages in fuel and pilots. The moment we started our attacks upon oil production in May 1944, the Germans began to find them- selves with more planes than they could fly. Their aircraft production began to lag only in the fall of 1944, after the aircraft industry had ceased to be a primary target for the Combined Bomber Offensive. And, as we have noted, the
major losses of German aircraft, together with trained pilots, occurred as a result of air battles which our bombing forays forced upon them and of our attacks on enemy airfields.
Possibly it was our method of attacking the aircraft target manufacturing rather than the choice of the system itself that was wrong. Hermann Goring and Albert Speer argued after their capture that aircraft-engine production would
U. S. S. B. S. , Airrraft Division Industry Report (Item #4 for European War), p. 6.
u. s:s. B. s. , Effects on German War Economy, p. 12.
have made a better target system than airframes, because the engines were made in a much smaller number of fac- tories. But others pointed out that engine-manufacturing plants were of much lower physical vulnerability than air- frame factories, especially to the light bombs (maximum 500 lbs. ) we were then using. @
The marked and immediate success achieved against the oil-producing industry seemed to indicate that the enemy air force was far more vulnerable through denial of liquid fuel than through direct attack upon it. The great fuel-pro- ducing plants could not be dispersed, their essential produc- ing facilities were quite vulnerable to blast and incendiary damage, and they were difficult to conceal. Yet only about
I per cent of the half-million tons of bombs dropped on Ger- many before May 1944 had been aimed at the oil industry. This omission resulted from the belief that the major fuel- producing plants lay beyond our range capabilities, from our consistent overestimation of the reserves of fuel which the Germans had in storage, and from our anxiety to get quick results. The total weight of bombs ultimately aimed at oil-
production facilities and storage depots was about 240,000 tons, or about half the total tonoage that had been dropped on Germany proper prior to May 1944.
Our failure to make a direct and comprehensive attack on the German chemical industry, including the synthetic-rub- ber plants, was also a serious error. The fact that that industry collapsed as a wholly unexpected result of our attack on oil reveals how vulnerable it was. Had we elevated it to the status of a target system in itself, we could have demolished
it much earlier in the war than we did and with only a small percentage of the bombs ultimately aimed at oil. The German
U. S. S. B. S. , Aircraft Division Report, pp. 53f.
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General Heinrici told our U. S. S. B. S. interrogators that if Allied effort had been concentrated on ammonia plants, Germany could have been knocked out of the war a full year
Bombing accuracy was greatly improved later on, espe- cially during the summer of 1944. Nevertheless, the limita- tions described above could be accepted, and a campaign carried out despite them, only if the attacker expected sub- stantial results from area bombing. Air Marshal Sir Arthur Harris of Bomber Command did expect such results, because, despite his utter disdain for what we now call "psychological warfare," he shared Douhet's faith in the critical vulnerability of civilian morale. We shall consider the effects of bombing on civilian morale in a separate section, though it should already be obvious that whatever morale decline took place was of limited effect upon the over-all strategic situation. There was immense destruction and damage wrought on the buildings in German cities, and it is really surprising that the
war industries gathered in those cities should have suffered so little impairment or loss of production.
The tonnages expended on city bombing were enormous. Prior to our oil offensive,53 per cent of the bombs dropped on Germany were aimed at area targets, and only 13 per cent at specific industries. Even during the oil offensive, over 27 per cent of the million-and-a-half tons dropped were aimed at cities and only 22 per cent at specific industries, the latter including the 16 per cent assigned to oil targets.
What were the results? The Report of the Area Studies Division of the U. S. S. B. S. opens with the following para- graph:
The major cities of Germany present a spectacle of destruction so appalling as to suggest a complete breakdown of all aspects of
War), pp. jf. This kind of inaccuracy, incidentally, is one reason why electric power stations, which Speer and others considered an extraor- dinarily choice target system, were not in fact targeted. The vulnerable portions of electric power stations generally take up a very small area.
earlier. ''
That may not be so, but it is an interesting opinion.
The Failure o f City Bombing in Germany
The bombing of cities turned out to be a great waste of effort. T o be sure, cities were easier to find and hit than were particular industrial plants, and the kind of weather encoun- tered over Germany often left no choice. Also we must re- member the special limitations imposed on the R. A. F. by the fact that it was built and equipped as a night-bombing force :
Prior to the development of long-range fighters and the discovery and improvement of non-visual bombing aids and techniques, the R A F could not undertake daylight bombing without prohibitive losses, nor could it achieve sufficient accuracy in night bombing to attack other than very large targets. Even with the earlier forms of radar, an attack on a target smaller than a city area of at least roo,ooo population was not economical.
For example, using "GEE," the first radar navigational aid (which became available in March 1gq2), Bomber Command of the RAF, in attacks on towns in the Ruhr, could drop approximately 50 per cent of its bombs within five miles of the aiming point and 10 per cent within two miles. This meant that only 5 to 10 per cent of the tonnage dispatched could be dropped on a town the size of Essen and only two to three per cent on the Krupp works within Essen. Thus, economy required that attacks be aimed at the city center, ensuring that the maximum tonnage of bombs would fall somewhere on the target. "
loU. S. S. B. S. , Powder, Explosives . . . (Item #III for European War:
Oil Division; Ministerial Report No. I ) , p. 4; see also Oil Division Final
Report, PP. 40-73.
l1U. S. S. B. S. ,Area Studies Division Report (Item #31 for European
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urban activity. On the first impression it would appear that the area attacks which laid waste these cities must have substantially eliminated the industrial capacity of Germany. Yet this was not the case. The attacks did not so reduce German war production as to have a decisive effect on the outcome of the war.
The reasons for this indecisive effect were several, and we can only mention a few. One was the fact that in most German cities the industrial areas were on the perimeter, and area attacks on previously unbombed cities were always aimed at the centers. Even with the considerable improvement in nonvisual bombing aids between 1943 and 1944, it was prac- tically impossible to concentrate bombing attacks upon the industrial portions of built-up areas. Where industrial plants were hit, the nonessential as well as the essential were affected. The halting of the former only helped to speed the flow of labor and other resources to the latter. Such essential services as electricity, gas, and water were disrupted by heavy attacks, but in most cases they were readily restored. The cutting of the Ruhr gas lines in 1944 shut down important plants in Diisseldorf, Essen, Krefeld, and Berlin and contributed to the collapse of German steel production, but that was an excep- tional occurrence. It must be remembered too that the same bombing which inevitably reduced some of the supply of essential utilities also reduced some of the demand.
Another important fact about city bombing is that the dam- age was done primarily to buildings rather than to the ma- chines or machine-tools which some of those buildings housed. Not more than an estimated 6 to 7 per cent of all machine tools in Germany were damaged or destroyed by air attack, and not all of those had to be replaced. "In 1944, the year of the heaviest bombing, it is estimated that it was necessary to devote only 10 to 12 per cent of machine tool
production to the repair of machine tools damaged as a result of air attack. "" If the buildings which housed machines im- portant to war production were too severely damaged, the machines often could be moved to other locations. Otherwise the structures were roughly patched up and the workers pre- vailed upon to continue.
We should not assume that the damage done to over-all production was trivial. An area raid could drive production
in a city down by as much as 55 per cent in the month im- mediately following the attack. But recovery was rapid; most ,
cities were back to 80 per cent of normal within three months, and had recovered com~letelywithin six to eleven months. Naturally the recovery was most rapid in the most essential industries. No doubt the "cushion" in consumer goods was being eroded away. No doubt, too, indirect effects, as ex- pressed in absenteeism of workers, were growing steadily more serious.
Certainly the terrible shock given to the entire German state by the series of extremely heavy attacks directed at Ham- burg at the end of July and the beginning of August 1943 suggests what might have happened if attacks of comparable intensity could have been directed also against a substantial
number of other German cities at about the same time and in rapid succession. There is clearly no basis at all for assum- ingthat conclusions about German urban bombing in World
War II would apply to war in the atomic age. A different re- sult, as we shall see, obtained even in the same war in the case of Japan. But the fact remains that "the over-all index of German munitions production increased steadily from
IOO in January 1942 to 322 in July 1944,"'~a period that in- cluded a tremendous amount of general city bombing.
U. S. S. B. S. , Area Studies Division Report, p. 22. 18Ibid. , p. 19.
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The bombing of German cities cost the Germans much in production and more in the diversion of military resources to defense; but we must nevertheless state that no critical shortages in war commodities of any kind are traceable to it. To cause inconvenience and unhappiness to the enemy is a reasonable military aim in war, but in view of the promises made by Douhet and his followers, and in view also of the great military resources invested in it, the urban-area bomb- ing of World War I1 must be set down unequivocally as a failure.
Trial and Error in Bombing Tactics
For World War I1 types of bombs it was necessary not only to pick the right target systems but also to find the right facilities within those systems and the right target centers within those facilities. In our attack upon railroad transpor- tation, for example, a large proportion of the bombing was directed against freight-car marshalling yards, and usually we aimed at the center of the yards in order to hit the great- est amount of trackage. As a result, such bombing usually left some fairly intact stump yards near the entrance to the original yards, which the Germans could use for high-prior- ity traffic while proceeding with repairs. The entrance, or throat, of the yard would have been a far better target center, but was rarely so designated. Moreover, the Germans not only had a large surplus capacity in yards, but some of the impor-
tant traffic, including troop movements, tended to use com- plete trains which did not require the use of marshalling yards at all. By far the most effective way of interdicting rail- road transportation, at least with the H. E. (high explosive) bombs of World War 11, proved to be by way of line cuts at bridges, underpasses, viaducts, tunnels, and the like. "
"At least this is the conclusion of the Transportauon Division of
Even in the successful offensive against the oil industry there was a generally poor selection of "ground-zeros"'" within the plants selected for attack. Although accuracy. in general was far below the "pickle-barrel" precision adver- tised before the war, vulnerable areas when chosen consist- ently as the bull's-eye were invariably destroyed. In only a small minority of the cases, however, were the most critical and vulnerable sections of the plant so chosen.
Also, the bombs used were usually too light for the job. The U. S. A. A. F. 's attacks were "based on the observation that it is easier to hit an elephant with a shotgun than with a rifle. " The average weight per unit of the bombs we dropped on oil and chemical targets was 388 pounds, but it was the heavy bombs of two to four thousand pounds each, used toward the very end of the war, which were alone able to do
really permanent damage to heavy industrial installations. The British, incidentally, were considerably more advanced than we in this respect, the average weight of the bombs dropped by the R. A. F. during our oil oflensive being some- thing like 660 pounds. A considerable improvement in effec-
U. S. S. B. S. The British Bombing Survey Unit credited much greater effec- tiveness to the bombing of marshalling yards, but, as we have noted, the Survey was directed by persons who had been deeply involved in the operational decisions.
l5 This awkward term is forced upon me by shifts in terminology since World War 11. What for bombing would correspond to the "bull's-eye" in pistol or rifle target shooting used to be called the "aiming point," which is the sense in which the latter term is used through most of the U. S. S. B. S. However, with the development of bombing sights that per- mitted offset bombing, the "aiming point" might well be miles from the center of the target (making it rather like the offset "aiming point" used in archery target shooting). The atomic bomb has encouraged the habit of using the term "ground zero" to indicate the point on the surface im-
mediately under the center of burst, and "designated ground zero," often abbreviated D. G.
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,
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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
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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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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.
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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
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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
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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.
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
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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. S. were more cautious, offering the opinion that "it is possible that production would have been 15-20per cent higher in the ab- sence of bombing. "'
In short, the attack on airframe production paid dividends -any diminution of enemy strength is a dividend-but they were not in the category of "decisive. " They did not bear out what had been promised for a concentrated offensiveby air forces of the size we were operating in early 1944. Moreover, we do not know how effectively the German Air Force could have used those "lost" aircraft, in view of shortages in fuel and pilots. The moment we started our attacks upon oil production in May 1944, the Germans began to find them- selves with more planes than they could fly. Their aircraft production began to lag only in the fall of 1944, after the aircraft industry had ceased to be a primary target for the Combined Bomber Offensive. And, as we have noted, the
major losses of German aircraft, together with trained pilots, occurred as a result of air battles which our bombing forays forced upon them and of our attacks on enemy airfields.
Possibly it was our method of attacking the aircraft target manufacturing rather than the choice of the system itself that was wrong. Hermann Goring and Albert Speer argued after their capture that aircraft-engine production would
U. S. S. B. S. , Airrraft Division Industry Report (Item #4 for European War), p. 6.
u. s:s. B. s. , Effects on German War Economy, p. 12.
have made a better target system than airframes, because the engines were made in a much smaller number of fac- tories. But others pointed out that engine-manufacturing plants were of much lower physical vulnerability than air- frame factories, especially to the light bombs (maximum 500 lbs. ) we were then using. @
The marked and immediate success achieved against the oil-producing industry seemed to indicate that the enemy air force was far more vulnerable through denial of liquid fuel than through direct attack upon it. The great fuel-pro- ducing plants could not be dispersed, their essential produc- ing facilities were quite vulnerable to blast and incendiary damage, and they were difficult to conceal. Yet only about
I per cent of the half-million tons of bombs dropped on Ger- many before May 1944 had been aimed at the oil industry. This omission resulted from the belief that the major fuel- producing plants lay beyond our range capabilities, from our consistent overestimation of the reserves of fuel which the Germans had in storage, and from our anxiety to get quick results. The total weight of bombs ultimately aimed at oil-
production facilities and storage depots was about 240,000 tons, or about half the total tonoage that had been dropped on Germany proper prior to May 1944.
Our failure to make a direct and comprehensive attack on the German chemical industry, including the synthetic-rub- ber plants, was also a serious error. The fact that that industry collapsed as a wholly unexpected result of our attack on oil reveals how vulnerable it was. Had we elevated it to the status of a target system in itself, we could have demolished
it much earlier in the war than we did and with only a small percentage of the bombs ultimately aimed at oil. The German
U. S. S. B. S. , Aircraft Division Report, pp. 53f.
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General Heinrici told our U. S. S. B. S. interrogators that if Allied effort had been concentrated on ammonia plants, Germany could have been knocked out of the war a full year
Bombing accuracy was greatly improved later on, espe- cially during the summer of 1944. Nevertheless, the limita- tions described above could be accepted, and a campaign carried out despite them, only if the attacker expected sub- stantial results from area bombing. Air Marshal Sir Arthur Harris of Bomber Command did expect such results, because, despite his utter disdain for what we now call "psychological warfare," he shared Douhet's faith in the critical vulnerability of civilian morale. We shall consider the effects of bombing on civilian morale in a separate section, though it should already be obvious that whatever morale decline took place was of limited effect upon the over-all strategic situation. There was immense destruction and damage wrought on the buildings in German cities, and it is really surprising that the
war industries gathered in those cities should have suffered so little impairment or loss of production.
The tonnages expended on city bombing were enormous. Prior to our oil offensive,53 per cent of the bombs dropped on Germany were aimed at area targets, and only 13 per cent at specific industries. Even during the oil offensive, over 27 per cent of the million-and-a-half tons dropped were aimed at cities and only 22 per cent at specific industries, the latter including the 16 per cent assigned to oil targets.
What were the results? The Report of the Area Studies Division of the U. S. S. B. S. opens with the following para- graph:
The major cities of Germany present a spectacle of destruction so appalling as to suggest a complete breakdown of all aspects of
War), pp. jf. This kind of inaccuracy, incidentally, is one reason why electric power stations, which Speer and others considered an extraor- dinarily choice target system, were not in fact targeted. The vulnerable portions of electric power stations generally take up a very small area.
earlier. ''
That may not be so, but it is an interesting opinion.
The Failure o f City Bombing in Germany
The bombing of cities turned out to be a great waste of effort. T o be sure, cities were easier to find and hit than were particular industrial plants, and the kind of weather encoun- tered over Germany often left no choice. Also we must re- member the special limitations imposed on the R. A. F. by the fact that it was built and equipped as a night-bombing force :
Prior to the development of long-range fighters and the discovery and improvement of non-visual bombing aids and techniques, the R A F could not undertake daylight bombing without prohibitive losses, nor could it achieve sufficient accuracy in night bombing to attack other than very large targets. Even with the earlier forms of radar, an attack on a target smaller than a city area of at least roo,ooo population was not economical.
For example, using "GEE," the first radar navigational aid (which became available in March 1gq2), Bomber Command of the RAF, in attacks on towns in the Ruhr, could drop approximately 50 per cent of its bombs within five miles of the aiming point and 10 per cent within two miles. This meant that only 5 to 10 per cent of the tonnage dispatched could be dropped on a town the size of Essen and only two to three per cent on the Krupp works within Essen. Thus, economy required that attacks be aimed at the city center, ensuring that the maximum tonnage of bombs would fall somewhere on the target. "
loU. S. S. B. S. , Powder, Explosives . . . (Item #III for European War:
Oil Division; Ministerial Report No. I ) , p. 4; see also Oil Division Final
Report, PP. 40-73.
l1U. S. S. B. S. ,Area Studies Division Report (Item #31 for European
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urban activity. On the first impression it would appear that the area attacks which laid waste these cities must have substantially eliminated the industrial capacity of Germany. Yet this was not the case. The attacks did not so reduce German war production as to have a decisive effect on the outcome of the war.
The reasons for this indecisive effect were several, and we can only mention a few. One was the fact that in most German cities the industrial areas were on the perimeter, and area attacks on previously unbombed cities were always aimed at the centers. Even with the considerable improvement in nonvisual bombing aids between 1943 and 1944, it was prac- tically impossible to concentrate bombing attacks upon the industrial portions of built-up areas. Where industrial plants were hit, the nonessential as well as the essential were affected. The halting of the former only helped to speed the flow of labor and other resources to the latter. Such essential services as electricity, gas, and water were disrupted by heavy attacks, but in most cases they were readily restored. The cutting of the Ruhr gas lines in 1944 shut down important plants in Diisseldorf, Essen, Krefeld, and Berlin and contributed to the collapse of German steel production, but that was an excep- tional occurrence. It must be remembered too that the same bombing which inevitably reduced some of the supply of essential utilities also reduced some of the demand.
Another important fact about city bombing is that the dam- age was done primarily to buildings rather than to the ma- chines or machine-tools which some of those buildings housed. Not more than an estimated 6 to 7 per cent of all machine tools in Germany were damaged or destroyed by air attack, and not all of those had to be replaced. "In 1944, the year of the heaviest bombing, it is estimated that it was necessary to devote only 10 to 12 per cent of machine tool
production to the repair of machine tools damaged as a result of air attack. "" If the buildings which housed machines im- portant to war production were too severely damaged, the machines often could be moved to other locations. Otherwise the structures were roughly patched up and the workers pre- vailed upon to continue.
We should not assume that the damage done to over-all production was trivial. An area raid could drive production
in a city down by as much as 55 per cent in the month im- mediately following the attack. But recovery was rapid; most ,
cities were back to 80 per cent of normal within three months, and had recovered com~letelywithin six to eleven months. Naturally the recovery was most rapid in the most essential industries. No doubt the "cushion" in consumer goods was being eroded away. No doubt, too, indirect effects, as ex- pressed in absenteeism of workers, were growing steadily more serious.
Certainly the terrible shock given to the entire German state by the series of extremely heavy attacks directed at Ham- burg at the end of July and the beginning of August 1943 suggests what might have happened if attacks of comparable intensity could have been directed also against a substantial
number of other German cities at about the same time and in rapid succession. There is clearly no basis at all for assum- ingthat conclusions about German urban bombing in World
War II would apply to war in the atomic age. A different re- sult, as we shall see, obtained even in the same war in the case of Japan. But the fact remains that "the over-all index of German munitions production increased steadily from
IOO in January 1942 to 322 in July 1944,"'~a period that in- cluded a tremendous amount of general city bombing.
U. S. S. B. S. , Area Studies Division Report, p. 22. 18Ibid. , p. 19.
123
? ORIGINS OF AIR STRATEGY
STRATEGIC BOMBING IN WORLD WAR I1
The bombing of German cities cost the Germans much in production and more in the diversion of military resources to defense; but we must nevertheless state that no critical shortages in war commodities of any kind are traceable to it. To cause inconvenience and unhappiness to the enemy is a reasonable military aim in war, but in view of the promises made by Douhet and his followers, and in view also of the great military resources invested in it, the urban-area bomb- ing of World War I1 must be set down unequivocally as a failure.
Trial and Error in Bombing Tactics
For World War I1 types of bombs it was necessary not only to pick the right target systems but also to find the right facilities within those systems and the right target centers within those facilities. In our attack upon railroad transpor- tation, for example, a large proportion of the bombing was directed against freight-car marshalling yards, and usually we aimed at the center of the yards in order to hit the great- est amount of trackage. As a result, such bombing usually left some fairly intact stump yards near the entrance to the original yards, which the Germans could use for high-prior- ity traffic while proceeding with repairs. The entrance, or throat, of the yard would have been a far better target center, but was rarely so designated. Moreover, the Germans not only had a large surplus capacity in yards, but some of the impor-
tant traffic, including troop movements, tended to use com- plete trains which did not require the use of marshalling yards at all. By far the most effective way of interdicting rail- road transportation, at least with the H. E. (high explosive) bombs of World War 11, proved to be by way of line cuts at bridges, underpasses, viaducts, tunnels, and the like. "
"At least this is the conclusion of the Transportauon Division of
Even in the successful offensive against the oil industry there was a generally poor selection of "ground-zeros"'" within the plants selected for attack. Although accuracy. in general was far below the "pickle-barrel" precision adver- tised before the war, vulnerable areas when chosen consist- ently as the bull's-eye were invariably destroyed. In only a small minority of the cases, however, were the most critical and vulnerable sections of the plant so chosen.
Also, the bombs used were usually too light for the job. The U. S. A. A. F. 's attacks were "based on the observation that it is easier to hit an elephant with a shotgun than with a rifle. " The average weight per unit of the bombs we dropped on oil and chemical targets was 388 pounds, but it was the heavy bombs of two to four thousand pounds each, used toward the very end of the war, which were alone able to do
really permanent damage to heavy industrial installations. The British, incidentally, were considerably more advanced than we in this respect, the average weight of the bombs dropped by the R. A. F. during our oil oflensive being some- thing like 660 pounds. A considerable improvement in effec-
U. S. S. B. S. The British Bombing Survey Unit credited much greater effec- tiveness to the bombing of marshalling yards, but, as we have noted, the Survey was directed by persons who had been deeply involved in the operational decisions.
l5 This awkward term is forced upon me by shifts in terminology since World War 11. What for bombing would correspond to the "bull's-eye" in pistol or rifle target shooting used to be called the "aiming point," which is the sense in which the latter term is used through most of the U. S. S. B. S. However, with the development of bombing sights that per- mitted offset bombing, the "aiming point" might well be miles from the center of the target (making it rather like the offset "aiming point" used in archery target shooting). The atomic bomb has encouraged the habit of using the term "ground zero" to indicate the point on the surface im-
mediately under the center of burst, and "designated ground zero," often abbreviated D. G.
