strategic air offensives

strategic air offensives.

1. Against Germany

The immediate origins of the campaign are to be found in the long-range bombing of the First World War. The Germans, who could not invade or effectively blockade the UK due to their relative lack of sea power, tried a direct attack by bombing. This was done by Zeppelins and increasingly, from May 1917, by aeroplanes, of which the Gotha was the most effective. These raids, and especially those of the Gothas on London in June and July 1917, caused alarm bordering on panic in Lloyd George's cabinet. Smuts was appointed to produce a solution to this new threat. His conclusion was that direct defence against long-range and high-level bombers, even in daylight, was not feasible and that the only answer was a counter-offensive of greater power. He thought this offensive would be so important that he recommended the creation of a new and separate fighting service with its own independent staff to bring the campaign into action. The result was the creation on 1 April 1918 of the Royal Air Force with the central task of waging a direct bombing offensive aimed at the sources of Germany's war effort, such as its war industries and transport system.

Little progress had been made towards a test by experience of what long-range bombers could achieve when the war was determined by conventional means in November 1918. This meant that those who were advocates of the decisive prospect of what soon became known as strategic bombing could not be proved by the sceptics to be wrong; it meant in effect that the British air staff, under the dynamic leadership of Marshal of the Royal Air Force Lord Trenchard (1873–1956), was able to develop a theory of war which said that victory would come to the power which mounted the heaviest and most sustained bombing offensive. To a large extent, however, the idea remained a theory as opposed to the basis of an experiment; the Conservative Party in the UK was reluctant to devote financial and industrial resources to the arming of the country and the Labour Party was inclined to fall in with the view that bombing should be declared illegal by international agreement. So while the air staff produced memoranda setting out in increasing detail how an enemy, and, in particular, the German, war economy could be destroyed by bombing, they had little scope for testing the plans by realistic air exercises. Such exercises as were held did reveal a substantial gap between what was aimed at and what was possible, but shortcomings were largely disregarded on the grounds that the force was inadequately trained and equipped and that the aircraft were of obsolete vintage.

Hitler's arrival in power in 1933 produced a rearmament policy in the UK and the air staff proposed to give an overriding priority to the expansion of Bomber Command, which was created in 1936. Though a heavy bomber specification was issued, which eventually produced the Stirling, the Halifax, and, via the Manchester, the Lancaster, this did not produce effective operational results until March 1942. Indeed, the government overruled the air staff's priority and substituted one in favour of fighters, which were much cheaper per unit and therefore produced better figures to announce in the Commons when the subject was air parity with the Luftwaffe.

When war broke out in September 1939 the British had much the most advanced doctrine of strategic bombing, but the Germans had the larger air force and the Americans, as events were soon to prove, had far the greatest long-term potential. As the USA was neutral, the Germans had no theory of strategic bombing, and the British were unwilling to provoke an air attack by what they saw as a more effective opponent, the strategic air offensive was deferred, but in this breathing-space, first the British and then the Germans thought they had learned the same lesson. This was that the vulnerability of heavy bombers to defending fighters meant that long-range bombing by day beyond the range of high-performance escorting fighters such as Me109s or Spitfires was not a feasible operation of war. When therefore, in May 1940, the desperate situation of the war on land drove the British to embark upon the long-planned strategic air attack on Germany, the Wellingtons, Whitleys, and Hampdens went into action at night. Similarly, when the Germans were frustrated in their attempt to destroy RAF Fighter Command in the battle of Britain, they too turned to night attack (see Blitz). The cover of darkness, which afforded the bombers a substantial degree of protection, also prevented the crews from seeing their targets, or indeed, for the greater part, getting anywhere near them. Thus, the original targets, which had been individual installations, such as oil plants or factories, or complexes, such as marshalling yards or dock areas, were abandoned in favour of larger ones. In the course of 1941, it became clear from photographic evidence (see Butt report) that the smallest targets which were operationally feasible at night with the aircraft and equipment in service were whole towns. Thus, the British had the choice between abandoning the bomber offensive, which at the time was the only available means of striking direct blows at Germany, or of adopting the policy of attacking the centres of large towns. In the situation of the war at the end of 1941, it is scarcely surprising that the latter course was selected and a tactical policy known as area bombing was adopted.

The British attack upon German towns was thus dictated by operational and tactical reasons, but there also seemed to be strong strategic arguments in favour of it. These were cogently urged in the government and in the Chiefs of Staff Committee by Churchill's scientific adviser, Lord Cherwell (see Lindemann), and they were readily accepted, and, indeed, also advocated by the chief of the air staff, Portal, and by Harris, who took over as AOC-in-C of Bomber Command in February 1942. Harris seized this new initiative by mounting dramatic fire raids on Lübeck and Rostock in the spring of 1942. At the end of May 1942 he called up the whole of his second line of operational training units and launched a thousand bombers in a single attack upon a single target, Cologne (see also thousand-bomber raids). Thereafter, with massive reinforcements of men and machines, the introduction of aids to navigation and bomb aiming (see electronic navigation systems), and the development of increasingly ingenious tactics, he embarked upon a systematic attempt to tear the heart out of the major German industrial and transport towns from the Ruhr to Berlin. In March 1942, serious damage was done in the Ruhr; in July 1943Hamburg was set alight and upwards of 40,000 people killed; and in November 1943 the prime aim was shifted to the middle of Berlin. Harris declared that the battle would cost Bomber Command 400–500 aircraft but that, if the Americans would come in on the attack, it would cost Germany the war.

During the air offensive against Berlin, between 18 November 1943 and 31 March 1944, Harris dispatched some 9,111 bomber sorties in 16 major attacks. He also sent another 11,113 against other major towns elsewhere for he could never concentrate exclusively on one target since that would have enabled the defences to concentrate too. From all these operations 1,047 bombers failed to return and a further 1,682 were damaged, many of them beyond repair. In the attacks on Berlin itself, 492 bombers were lost. These losses had to be viewed in the context of the front-line strength of Bomber Command, which, throughout the battle, averaged, some 892 bombers. If Bomber Command was to survive as an effective fighting force, this was a casualty rate which could not be sustained. The battle had to be broken off; moreover, though Berlin and many other German towns suffered catastrophic damage, it did not cost Germany the war. On the contrary, a self-destructive element in the British night area offensive began to appear. In the race between, on the one hand, the admittedly vast destructive power which Bomber Command had now developed and, on the other, the resilience, ingenuity, and rate of repair on the German part, it was the latter which was beginning to win. Yet through one of the great ironies of military history, Bomber Command was on the verge of its greatest triumph.

The Americans hardly came in on the air offensive against Berlin, for the simple reason that they were unable in this period to mount sustained attacks on German targets. The problem which this created for them is the key to the outcome of the strategic air attack on Germany. Arnold, the commanding general of the United States Army Air Forces (USAAF), had been greatly impressed by the British theory of strategic bombing, but neither he nor his subordinates thought much of the tactics or the results of night area bombing. Moreover the principal American bomber, the B17, was unsuited to night flying. The Americans determined to mount their attack in daylight, which they thought would enable them to employ precision bombing methods to hit ‘pinpoint’ targets, such as oil installations, aircraft factories, and, above all ball bearing plants. Thus they would achieve with the surgeon's knife what the British had been driven to attempt by the sledgehammer. Despite British attempts to convince them that heavy bombers could not stand up to high performance short-range fighters, the Americans built up in England within the Eighth USAAF a formidable bomber force under Eaker's command and in October 1943 the Fifteenth USAAF was activated in Italy, for use mainly against targets in northern Italy and the Balkans. From August 1942 onwards Eaker's B17s and B24s rehearsed the part, usually within range of fighter cover, over targets in France. In January 1943, soon after the Combined Bomber Offensive was discussed and approved at the Casablanca conference (see SYMBOL), they flew beyond the range of friendly fighters and opened their attack on German targets. A series of disasters culminated in a raid on the ball bearing plants at Schweinfurt on 14th October 1943 from which, out of a force of 291 bombers, 60 failed to return and more than 100 others were damaged. This showed that the British warning had been right; the Americans had to break off the attack and the German war economy continued to function with remarkable efficiency.

Instead of turning to night attack, as in like circumstances the British had done, the Americans adopted a second and radical alternative. This was the provision of fighter cover for the day bombers all the way from base to target and back even at the longest ranges, including Berlin. Though the British had pronounced such an idea a technical impossibility (they believed that a fighter given the range of bomber would cease to be a fighter), the Americans found a solution in an aircraft which had originally been built in the USA, rejected by the American authorities and bought by the British—the P51 Mustang. Re-engined with a Packard Merlin and progressively equipped with longer and longer range droppable petrol tanks, strong forces of Mustangs were able to fly from British bases by the end of March 1944 and match, and usually outmatch, anything German, even at the extreme range of Berlin. By the end of the war, some 14,000 of these aircraft had been produced in the USA. This changed the prospects of long-range daylight bombing and indirectly it released the potential of night bombing as well.

The Eighth USAAF bombers, now, with Fifteenth USAAF, under Spaatz's overall command, were used to draw up the German defending fighters which were then engaged by his Mustangs at long range or by other types at shorter range. In the great air battles from January 1944 onwards, the Americans gradually wore down the Luftwaffe and began to establish an increasing degree of air superiority (see Big Week), enabling the American bombers to begin systematic bombing operations without prohibitive casualties. The decline of the Luftwaffe then began to engulf the night fighter force and from September 1944 onwards there was diminishing resistance to Bomber Command's night attacks. Thus, the way was opened for an effective bombing offensive against Germany by day and night.

In this final phase British Bomber Command, which could now regularly dispatch a thousand front-line bombers, most of them Lancasters, developed a destructive power and an accuracy of aim at night which far exceeded what the American B17s and B24s could do in daylight. Techniques of bombing, notably those developed by Group Captain Leonard Cheshire on principles which had first been indicated by Wing Commander Guy Gibson in the Dam Busters raid of May 1943, enabled Bomber Command to devastate relatively small targets and especially oil refineries, or, alternatively, to achieve fearful concentrations of destruction in area attacks on towns, which culminated in the ruin of Dresden in February 1945. The effort was, however, unduly dispersed between the top objects and within the former group between the alternatives of attacks on oil and on other industrial and communications targets. This was due to severe and unresolved differences of opinion between Portal, who was now convinced that oil was the best target, Tedder, who favoured transport, and Harris who adhered to the policy of general area bombing against the main towns. With bitter experience on his side, Harris was sceptical of intelligence, which got nearly everything except the German oil position wrong, and of ‘panacea’ solutions to the problem of cracking the German war economy.

Despite these differences, and the enormous diversion of effort into supporting the land forces launching the Normandy landings (see OVERLORD), British Bomber Command and the Eighth USAAF did produce an oil famine in Germany, the collapse of its transport system, and a fearful levelling of most of its great cities. These results were too late to win the war on their own, but they did make a decisive contribution to the defeat of Germany which could not have been achieved without the campaign in which Spaatz brought the Luftwaffe to action and defeated it.

The strategic air offensive against Germany cost the lives of about 50,000 British aircrew and a like number of Americans. It resulted in the death of between 750,000 and a million Germans. The destruction of the German war economy, which was eventually achieved, proved to be a far more formidable task than even cautious advocates had estimated. Spaatz stands out as the most brilliant commander, since it was he who grasped the principle that the way to victory lay in the achievement of command of the air and that the only effective method was the pursuit of the air battle. On Harris's side it must be recognized that intelligence estimates of German dependence on this or that commodity were usually wrong and, on Tedder's, that his policies related the air effort more directly to the operations of the armies, thus, as he put it, exploiting the common denominator factor. Portal, too, often the victim of bad intelligence, was certainly right in the end when he accepted their view of the German oil position. Arnold created and sustained an independent air effort on the part of what was still, theoretically, a subordinate service.

Strategic Air Offensive (Germany): RAF Bomber Command and EighthUSAAF: sorties flown, approximate tonnage of bombs dropped, andoperational losses, September 1939–May 1945

Sources: Webster, C. and Frankland, N., The Strategic Offensive against Germany, 1939–45, Vol. 4, (London, 1961), and Freeman, R., The US Strategic Bomber (London, 1975).
The figures shown in brackets after RAF Bomber Command's monthly losses were those lost in crashes and are included in the monthly total. The figures for total losses before March 1942 are unreliable as it is not known if all the aircraft which crashed had to be written off. Sorties flown for sea and flying bomb patrols, and for minelaying and Special Duties, are not included. The figures shown in brackets after Eighth USAAF monthly losses were those aircraft lost operationally for reasons other than being shot down by hostile A-A fire or aircraft, and they are included in the monthly total of losses.
a only night raids mounted during these months
A = number of sorties, B = approximate tonnage of bombs dropped in long tons,
C = operational losses.
	RAF Bomber Command	Eighth USAAF
Dates	A	B	C	A	B	C
1939
Sep	123	6	17(3)	–	–	–
Oct	32a	–	4(2)	–	–	–
Nov	19	–	1(1)	–	–	–
Dec	159	25	19(2)	–	–	–
1940
Jan	44	1	0	–	–	–
Feb	58	1	3(2)	–	–	–
Mar	292	31	12(6)	–	–	–
Apr	656	112	41(8)	–	–	–
May	2,419	1,668	76(6)	–	–	–
Jun	3,296	2,300	65(8)	–	–	–
Jul	2,338	1,257	79(7)	–	–	–
Aug	2,605	1,365	81(11)	–	–	–
Sep	3,239	2,339	87(21)	–	–	–
Oct	2,414	1,651	60(32)	–	–	–
Nov	2,007	1,316	86(34)	–	–	–
Dec	1,441	992	62(23)	–	–	–
1941
Jan	1,126	777	27(13)	–	–	–
Feb	1,741	1,431	52(34)	–	–	–
Mar	1,890	1,744	75(36)	–	–	–
Apr	2,925	2,396	98(19)	–	–	–
May	2,689	2,846	76(17)	–	–	–
Jun	3,759	4,310	116(18)	–	–	–
Jul	3,825	4,384	188(31)	–	–	–
Aug	3,812	4,242	206(50)	–	–	–
Sep	2,884	2,889	153(63)	–	–	–
Oct	2,639	2,984	126(41)	–	–	–
Nov	1,756	1,907	104(21)	–	–	–
Dec	1,562	1,794	51(16)	–	–	–
1942
Jan	2,240	2,292	88(32)	–	–	–
Feb	1,414	1,011	48(15)	–	–	–
Mar	2,355	2,675	101(21)	–	–	–
Apr	3,998	4,433	174(31)	–	–	–
May	2,807	3,234	136(21)	–	–	–
Jun	4,997	6,845	241(40)	–	–	–
Jul	4,227	6,368	212(22)	–	–	–
Aug	2,640	4,162	173(21)	114	151	–
Sep	3,616	5,595	214(39)	183	188	2(0)
Oct	2,604	3,809	130(27)	284	278	10(2)
Nov	2,194	2,423	87(23)	519	604	13(3)
Dec	1,958	2,714	112(24)	353	340	17(0)
1943
Jan	2,962	4,345	122(21)	338	594	18(0)
Feb	5,456	10,959	132(25)	526	568	23(2)
Mar	5,458	10,591	194(26)	956	1,483	21(3)
Apr	5,887	11,467	290(25)	449	858	29
May	5,490	12,920	284(31)	1,672	2,555	69(8)
Jun	5,816a	15,271	290(15)	2,107	2,330	90(0)
Jul	6,170a	16,830	219(31)	2,829	3,475	118(10)
Aug	7,807a	20,149	308(33)	2,265	3,999	117(10)
Sep	5,513a	14,855	225(34)	3,259	7,369	98(27)
Oct	4,638a	13,773	180(21)	2,831	4,548	186(9)
Nov	5,208a	14,495	210(48)	4,157	5,751	95(17)
Dec	4,123a	11,802	217(47)	5,973	10,655	172(22)
1944
Jan	6,278a	18,428	352(38)	6,367	10,532	203(37)
Feb	4,308	12,054	223(24)	9,884	16,480	271(20)
Mar	9,049	27,698	322(39)	11,590	19,892	345(55)
Apr	9,883	33,496	239(25)	14,464	22,447	420(1)
May	11,369	37,252	303(29)	19,825	32,450	376(43)
Jun	15,963	57,267	335(30)	28,925	54,204	320(46)
Jul	17,798	57,615	274(33)	23,917	40,784	352(71)
Aug	20,284	65,855	244(23)	22,967	44,120	331(32)
Sep	16,071	52,587	152(15)	18,268	36,332	374(30)
Oct	16,906	61,204	153(26)	19,082	38,961	177(29)
Nov	14,644	53,022	173(34)	17,003	36,091	209(13)
Dec	14,895	49,040	162(43)	18,252	36,826	119(17)
1945
Jan	10,907	32,923	190(57)	17,702	34,891	314(43)
Feb	17,400	45,889	233(60)	22,884	46,088	196(25)
Mar	21,191	67,637	301(86)	31,169	65,962	266(39)
Apr	13,823	34,954	108(35)	20,154	41,632	190(41)
May	1,417	337	6(1)	2,276	—	7(2)
total	373,514	955,044	10,123(1,796)	332,904	621,877	5,548(657)

Noble Frankland

2. Against Europe outside Germany

The Allied strategic air offensive in Europe, though directed mainly at Germany, also involved attacks on targets in occupied countries used for the German war effort, and on Germany's allies and satellites. Italian cities were subject to intermittent attack from 1940 onwards; a great deal of bombing in the autumn and winter of 1942–3 was directed at the submarine bases and facilities in France; and from late 1943 the Fifteenth US Army Air Force based in Italy attacked targets from the southern French coast to the Black Sea.

The attacks on occupied areas and on Germany's allies fulfilled the same purposes as the attacks on Germany itself: they were designed to destroy military and economic targets deemed vital to the Axis war effort. The bulk of the attacks outside German soil were against heavy industrial targets, the oil industry, and the European transport network. Many of the attacks on transport were tactical rather than strategic in character, preparing the way for the Allied assault on Sicily and then the Italian mainland, and in 1944 preparing the way for the Normandy landings. Towards the end of the war transport attacks became more strategic in purpose, disrupting rail links between industrial centres or destroying the supply routes for essential raw materials out of the Balkans or Italy.

The bombing of Italy followed very much the same pattern as the offensive against Germany. In 1940 RAF Bomber Command launched small and largely ineffective attacks against Italy's northern industrial cities. In the light of all the difficulties encountered in attacking such distant targets with any accuracy, the RAF adopted morale as the key target, and area bombing of key industrial suburbs as the instrument. When bases were secured in 1942 and early 1943 for attacks from the Mediterranean, both British and American bombers attacked Italian industry by day and night, bringing high casualties and a calculated reduction of Italian industrial output of 60% by the time Italy capitulated in September 1943. Much of this loss was due to widespread panic among the urban populations which had been left virtually defenceless against air attack. After Italy's surrender the Allies kept up the bombing of the northern part occupied by the Germans and more than 50,000 Italians were killed in these raids. Much of the later bombing was undertaken by the Fifteenth USAAF which attacked steel and ball-bearing production in Milan, Genoa, and Turin.

Strategic Air Offensive (Europe): Fifteenth USAAF: sorties flown, tonnage of bombs dropped, and operational losses, November 1943–May 1945

H = high explosive, I = incendiary
Source: Freeman, R., The US Strategic Bomber (London, 1975).
Dates	Sorties	Bombs dropped	Operational losses
1943		H	I
Nov	1,785	5,392	–	28
Dec	2,039	7,752	–	36
1944
Jan	4,720	11,051	–	54
Feb	3,981	6,611	136	128
Mar	5,996	9,842	534	85
Apr	10,182	20,657	599	194
May	14,432	29,606	749	175
Jun	11,761	23,637	829	196
Jul	12,642	30,621	1,562	317
Aug	12,194	27,660	179	254
Sep	10,056	20,645	211	94
Oct	9,567	15,712	545	140
Nov	9,259	16,153	1,144	132
Dec	10,050	18,308	449	205
1945
Jan	4,002	6,784	–	88
Feb	13,444	24,417	91	147
Mar	14,939	30,265	–	149
Apr	15,846	29,181	77	83
May	42	84		14
totals	166,937	334,378	7,105	2,519

The bombing of occupied Europe raised more delicate issues. The Allies were aware that bombing would bring civilian casualties and so might alienate the very populations they were trying to liberate. Attacks on France began in earnest in 1942, but were governed by a directive agreed between the British and Americans that they would be confined only to clearly identified military targets and that every effort was to be made to avoid hitting civilian targets in the vicinity. This proved impossible in practice. From October 1942 to the spring of 1943 top priority was given to bombing the German submarine bases in St Nazaire, Lorient, Brest, and La Pallice. The attacks by day and night utterly destroyed the towns surrounding the submarine pens but did virtually no damage to the targets themselves. Harris, RAF Bomber Command's C-in-C, regarded the attacks as ‘completely wasteful’, and after the spring the bombers were increasingly used against industrial targets in France, disrupting much of the work being done for the Germans in the French aircraft and motor industries. It was in France that the Eighth USAAF, based in the UK, began its bombing career, testing the American tactics of daylight bombing of precision targets against light resistance. The lessons learned in France convinced its commander, Eaker, that daylight attacks were ‘feasible and practicable’.

The same tactics were adopted by the Fifteenth USAAF when it was activated in southern Italy in October 1943. Its purpose was primarily to contribute to the aims of the Combined Bomber Offensive in attacking German oil supplies, the aircraft industry, and transport. The most important attacks were against the Romanian oilfields at Ploesti. First attacked in August 1943, the oilfields were repeatedly bombed until August the following year when production ceased. The Fifteenth USAAF dropped 13,469 tons of bombs on Ploesti, but lost 350 heavy bombers in the effort. The loss rates for the Fifteenth were higher than those of the Eighth, partly because the oil targets were so well-defended, partly because of the dangers of long flights over mountainous terrain. The Fifteenth also attacked a wide range of other oil targets, damaging, by June 1944, 29 out of the 60 oil refineries within its range. The bombers, sometimes by shuttle bombing, also attacked industrial and transport targets in Hungary, Czechoslovakia, Yugoslavia, and Greece. Only at this later stage of the war did Austria come within range of Allied bombers, and much less damage was inflicted on Austrian cities and industries than was the case elsewhere in Greater Germany. The exception was the industrial area of Wiener Neustadt where the large Messerschmitt aircraft factories became a key target in 1944. After Vichy France was occupied in November 1942 attacks were started against oil and industrial targets in southern France. American experience in the southern theatre showed that despite efforts to bomb precisely, they only achieved the area bombing of selected targets instead, and, in Germany, it proved impossible to separate the material from the moral target, to destroy factories without killing workers. More French and Italian citizens were killed by bombing than Britons.

Richard Overy

3. Against Japan

The strategic air offensive against Japan began on 15 June 1944 when 50 B29 Superfortresses of the Twentieth US Army Air Force bombed steel mills at Yawata, Kyūshū. Over the course of the next fifteen months, B29s would bring the war home to all of Japan with cruel and shocking effectiveness, destroying its cities, laying waste its industrial capacity, killing hundreds of thousands of its citizens, and finally delivering the atomic bombs that forced the unconditional surrender of its armed forces.

This great aerial assault rested on the wings of the new B29. Ready for action by early 1944, the huge plane could carry a greater bomb-load over longer distances than any other aircraft. But the Superfortresses required bases within 2,575 km. (1,600 mi.) of the Japanese home islands in order to strike the heart of their target. These became available that summer with the seizure of the Mariana Islands which were within B29 range of Tokyo and all other important Japanese cities.

The general strategy of the bombing campaign had been approved by Roosevelt and Churchill at the Cairo conference in December 1943 (see SEXTANT), and final plans were completed by the US Joint Chiefs of Staff the following April. The implementing agent was the newly created Twentieth USAAF, an independent organization operating directly under the control of General Arnold, commander of the US Army Air Forces.

Until the Marianas could be captured and developed as a base, the air offensive would be launched from India. The B29s would stage through central China to strike iron and steel targets in Manchukuo and south-western Japan. But these attacks were subject to severe logistical limitations and in any event could reach only as far as Kyūshū. They were thus simply a temporary measure until occupation of the Marianas allowed a full-scale assault on all of Japan.

On 15 June 1944, even as the invasion of the Marianas began, B29s of Twentieth USAAF's 20th Bomber Command struck Kyūshū from China. The China-based raids, however, proved of limited value. Of nearly 50 B29 attacks flown from China in 1944 and early 1945, only nine actually hit Japan, and these and others against targets in Manchukuo, Korea, China, Formosa, and South-East Asia did little strategic damage. They provided valuable experience for the bomber crews, but otherwise hardly justified their cost and effort.

The first B29 attack from the Marianas came on 24 November 1944. Approximately 80 unescorted Superfortresses of Twentieth USAAF's 21st Bomber Command, commanded by Brig-General Haywood S. Hansell, struck Tokyo's Nakajima aircraft factory in the first of a series of raids designed to cripple the Japanese aircraft industry. For the next two months Hansell, an outspoken advocate of precision bombing, carried out high-level daylight precision attacks on aircraft plants in Tokyo and Nagoya. These attacks were severely hampered by bad weather, extremely strong winds, mechanical difficulties with the new B29s, and losses to Japanese fighters. While they none the less inflicted considerable damage and lowered Japanese aircraft production, this was not immediately evident since poor weather and heavy cloud cover limited photographic reconnaissance.

The apparent inability of 21st Bomber Command to inflict greater damage brought increasing criticism from General Arnold in Washington. Arnold questioned the value of continued precision bombing efforts and urged the initiation of massive fire-bombing raids against Japan's inflammable cities. Flying at night at low altitudes, the incendiary attacks could carry a heavier bomb-load, avoid opposing fighters in the dark, and spread destruction over huge areas. The indiscriminate nature of these raids was exactly the effect that Hansell was determined to avoid. In mid-December, however, Arnold ordered him to make a full-scale incendiary attack on the city of Nagoya.

Hansell protested vigorously, but carried out the raid on 3 January 1945. The results were inconclusive. By comparison, a heavy precision bombing attack on a town near Kobe two weeks later was extremely effective, knocking out a major aircraft production facility.

By now, however, Arnold had decided to relieve Hansell. On 20 January, he replaced him with Maj-General Curtis E. LeMay, who had headed 20th Bomber Command in India and China. In his new command, LeMay continued to fly the high-level precision attacks but began to mix in a few incendiary raids. Although the latter were flown in daylight at high altitudes, they showed impressive results and Arnold directed that they be increased.

On 25 February, some 150 B29s carried out a huge incendiary attack on Tokyo, burning out over two and a half square kilometres (nearly a square mile) of the city. LeMay thereupon decided to make a major tactical change designed to further increase effectiveness. In place of the high-level daylight raids, he would have his bombers attack at night at low altitudes. They would thus escape the clouds and strong winds encountered on high as well as the Japanese fighter planes that had plagued daylight missions. Flying at low altitudes also reduced engine strain and fuel consumption, allowing the Superfortresses to carry more bombs. And without enemy fighter opposition, most of the B29 gunners, along with their weapons and ammunition, could be left behind, further increasing the feasible bomb-load. This drastic change in tactics would prove to be one of the most important innovations of the war (see bombers, 2).

On the night of 9/10 March 1945 nearly 300 B29's dropped about 2,000 tons of incendiaries on Tokyo. Attacking at altitudes of from 1,500–2,750 m. (5,000–9,000 ft.) for almost two hours they spread fires over a densely populated area. The flames, fanned by winds, became a vast firestorm that destroyed a quarter of the city, including more than 20 important industrial targets, killing nearly 85,000 Japanese civilians and injuring tens of thousands more.

Over the next ten days, similar incendiary attacks burnt out large sections of Nagoya, Kobe, and Osaka. Two more fire raids struck the Tokyo–Kawasaki area before the B29s were diverted to support the April invasion of Okinawa. By mid-May, however, 21st Bomber Command had been reinforced and resupplied and long-range P51 fighter escorts were flying from newly captured Iwo Jima, midway on the attack route.

For a month beginning on 14 May, B29s ravaged Japan's six most important industrial cities. Tokyo, Nagoya, Kobe, Osaka, Yokohama, and Kawasaki were reduced to smouldering ruins in nine devastating 500-bomber incendiary assaults. More than 100,000 civilians were killed and millions of others rendered homeless or forced to flee. Some of these attacks were daylight raids, which lured defending Japanese fighter planes into uneven combat with the escorting American P51s. By early June, so many of the defenders had been shot down that the Japanese grounded their remaining fighters to preserve them for use against the expected invasion of their homeland. LeMay now began a furious assault on 60 smaller Japanese cities and towns. These attacks were primarily incendiary strikes, but high-level precision raids on selected oil refineries and other targets destroyed the Japanese oil industry and inflicted further damage elsewhere. The tempo of these assaults was not at all slowed by an organizational change on 16 July 1945 when, in preparation for a planned invasion of Japan, Twentieth USAAF became the nucleus of the newly created US Army Strategic Air Forces (USASTAF), commanded by General Spaatz.

By the end of July, the B29s had just about run out of targets. Almost every Japanese city and large town had been devastated and all normal processes completely disrupted. The nation's economy was shattered, its industry crippled, transport and communication fragmented, and war production cut by more than half. Civilian casualties exceeded 800,000, including 300,000 dead; an estimated 8.5 million or more were rendered homeless. But the most important impact of the strategic air offensive was its effect on Japan's willingness to continue the war.

The punishing bombing campaign had raised serious concerns within the Japanese civilian leadership about the wisdom of continuing to fight. Although military domination of the government prevented any real steps towards peace, by April 1945 Emperor Hirohito had become determined to end the struggle somehow. Military leaders, however, remained adamant in their belief that if Japan could survive the B29 attacks, high American casualties in the expected invasion would bring a negotiated peace on relatively favourable terms. The official Japanese response to the Allied ultimatum contained in the 26 July Potsdam Declaration (see TERMINAL) was therefore simply to ignore it.

The atomic bombing of Hiroshima and Nagasaki on 6 and 9 August, along with the Soviet entry into the war on 8– 9 August (see Japanese–Soviet campaigns), brought matters rapidly to a head. Despite the continued opposition of his military chiefs, the emperor took the unprecedented step of announcing his decision to yield to Allied demands. On 14 August he directed that Japan should accept the Potsdam Declaration and surrender. The crushing fury of the B29 attacks, the mounting horror and devastation of the great fire raids, and the shocking atomic destruction of Hiroshima and Nagasaki had finally ended the war.

Strategic Air Offensive (Japan): Twentieth USAAF B29 losses and estimated tonnage of bombs dropped, April 1944–August 1945

aunconfirmed
Source: Freeman, R., The US Strategic Bomber (London, 1975).
A = combat losses, B = non-combat losses, C = estimated tonnage of bombs dropped
	20th Bomber Command	21st Bomber Command
Dates	A	B	C	A	B	C
1944
Apr	–	7a	–	–	–	–
May	–	5	–	–	–	–
Jun	10	8	547	–	–	–
Jul	3	5	209	–	–	–
Aug	14	5	252	–	–	–
Sep	3	7	521	–	–	–
Oct	5	16	1,669	–	–	–
Nov	19	2	1,631	4	5	575
Dec	16	6	1,556	21	6	2,105
1945
Jan	4	3	2,006	27	–	1,404
Feb	4	2	1,865	26	3	2,155
Mar	2	1	1,436	34	–	13,847
Apr	–	–	–	57	1	117,492
May	–	–	–	88	3	24,285
Jun	–	–	–	44	7	32,542
Jul	–	–	–	22	5	42,551
Aug	–	–	–	11	7	21,029
totals	80	67	11,691	334	37	157,985

Stanley L. Falk

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