The dispute over day and night bombing

According to popular chronologies of the war, on 6 October 1942 the Allies divided the work “by mutual agreement”: the Americans would bomb Germany by day and RAF Bomber Command by night. In fact no such agreement was concluded on that day. In the autumn of 1942 the division between day and night existed only in practice, since each air force flew in its own way, and the question itself was the subject of a sharp dispute. The British, led by Prime Minister Winston Churchill and the head of Bomber Command, Arthur Harris, doubted the American doctrine of daylight precision bombing and urged their ally to join the night offensive. A common policy, in which day and night raids were to complement each other, was adopted by the Combined Chiefs of Staff only at the Casablanca Conference in January 1943, and refined in the Pointblank directive in June 1943.

Two doctrines

The British had come to night bombing through bitter experience. In December 1939 Wellingtons were decimated over the Heligoland Bight, and in 1941 daylight sorties by a handful of American B-17Cs, known in the RAF as the Fortress I, ended in failure. At night the bombers were safer but hit little. After the Butt Report of August 1941, which showed that only about one aircraft in three dropped its bombs within five miles (some eight kilometres) of the target, the RAF switched to area bombing of entire industrial districts. From February 1942 it was directed by Harris, who in the spring and summer demonstrated the power of the method with the thousand-bomber raid on Cologne and in September with the devastation of Düsseldorf.

The US Army Air Forces had been raised on a different theory. For years the Air Corps Tactical School at Maxwell Field taught that heavy, well-armed bombers flying in tight formation could defend themselves against fighters, and that the Norden bombsight would allow them to hit individual factories, power stations and railway junctions from high altitude. Such attacks were meant to destroy the “bottlenecks” of the German economy rather than whole cities. The new Boeing B-17E and F Flying Fortress and the Consolidated B-24 Liberator carried a dozen or so machine guns and were designed for daylight operations, and their crews had not been trained in night navigation. Switching to night operations would have meant for the Americans not only a change of tactics but also the rebuilding of aircraft and training.

British doubts

From the summer of 1942 the Eighth Air Force of Major General Carl Spaatz was based in England, with its bomber force commanded by Brigadier General Ira Eaker. After the first B-17 raid on Rouen on 17 August, the Americans had flown a dozen or so missions by the beginning of October, but all of them were short, against targets in France and the Netherlands, mostly under the cover of British Spitfires. Not a single American bomber had yet flown over Germany. For the British, who were losing crews over the Reich every night, this was an argument that the American doctrine had not yet faced a real test.

Churchill made no secret of his disappointment. He had expected hundreds of American bombers to add quickly to the weight of attack on Germany, and instead he saw small groups flying rarely and not far. According to historians of the British bomber offensive, in the autumn of 1942 the Prime Minister was inclined to ask President Franklin Delano Roosevelt to switch the B-17s to night operations or to send them to fight the U-boats in the Atlantic. Harris, although personally a friend of Eaker’s who had helped him set up his command, regarded unescorted daylight raids over Germany as a costly mistake. The British aviation press, too, was sceptical. The well-known commentator Peter Masefield wrote that a deep daylight attack would be possible only once the enemy’s fighters had first been defeated.

The Chief of the Air Staff, Air Chief Marshal Charles Portal, and the Secretary of State for Air, Archibald Sinclair, took a different line. They too had doubts, but they warned Churchill that public pressure to change the doctrine would offend the Americans and might result in some of the promised bombers going to the Pacific instead of England. They advised giving the ally time.

Arnold under pressure

On the other side of the Atlantic, the commanding general of the Army Air Forces, General Henry H. Arnold, needed a success just as urgently. The Navy and the commanders in the Pacific were demanding aircraft for the war against Japan, and since August the Eighth Air Force had been giving up men and machines for the planned landings in North Africa. For Arnold, abandoning daylight raids would have meant admitting that the doctrine on which the whole American bomber force had been built had failed, and it would have undermined his efforts to win independence for the air force. Spaatz and Eaker assured him that with enough aircraft they could hit the Reich’s key industrial plants by day. Earlier, on 29 September, they had also taken over the RAF’s three Eagle Squadrons, which strengthened the American fighter force in England.

The test over Lille

The first serious test was the raid of 9 October 1942 on industrial plants in Lille in northern France: the steelworks and engineering works of the Compagnie de Fives-Lille and the locomotive works at Hellemmes. According to the American official history, 108 heavy bombers were dispatched, the largest number on any Eighth Air Force mission so far. Liberators of the 93rd Bombardment Group went into action for the first time. Many aircraft turned back, however, because of mechanical faults and crew inexperience, so that 69 aircraft attacked the primary target. Four bombers failed to return: three B-17s and one B-24.

The results were disappointing. According to the same official history, of the 588 high-explosive bombs dropped on Lille only nine fell within 1,500 feet (about 450 metres) of the aiming points, and many failed to explode. The bombs destroyed houses around the factories; some 40 French civilians were killed and about 90 injured. The gunners’ reports proved even more misleading. The crews claimed 56 German fighters destroyed, 26 probably destroyed and 20 damaged. In January 1943 these figures were reduced to 21 destroyed, and German records indicate that the Luftwaffe most probably lost only two aircraft that day. The inflation arose because many gunners in different bombers fired at the same fighter at once, and each reported his own success.

Even so, each side of the dispute read Lille in its own way. Eaker concluded that bombers flying in a strong formation could operate effectively even without fighter cover, and the false reports of dozens of kills seemed to bear this out. Even Masefield conceded after the raid that the question of whether the daylight air war could be carried over Germany needed a fresh answer. The sceptics pointed to the scattering of the bombs and the civilian casualties. After 9 October the weather turned bad, and the Eighth Air Force was giving up more groups for Operation Torch. Before November it flew only one more raid, on 21 October against the U-boat base at Lorient. On 25 October Arnold demanded an explanation of why his bombers were flying so seldom.

Place in the war

The matter was settled at the Casablanca Conference. In January 1943 Churchill was ready to ask Roosevelt to switch the Americans to night bombing. Arnold sent for Eaker, who handed the Prime Minister a one-page memorandum. In it Eaker argued that if the RAF bombed by night and the Americans by day, Germany would be bombed “round the clock” and the devil would get no rest. Churchill accepted the argument and agreed to give the Americans their chance. The Combined Chiefs of Staff directive of 21 January 1943, passed to Harris by the Air Ministry on 4 February, ordered that Germany also be attacked by day, in order to destroy targets unsuitable for night attack. The first American raid on a target in Germany, against Wilhelmshaven, took place on 27 January 1943. In June 1943 the Pointblank directive gave first priority to the destruction of the German fighter force, and the Combined Bomber Offensive took its final shape.

The dispute, however, never died down for the rest of the war. In the summer and autumn of 1943, over Schweinfurt and Regensburg, the Eighth Air Force lost dozens of bombers in a single day, proving that without escort a daylight raid deep into Germany was too costly. The situation changed only with the arrival of long-range escort fighters at the beginning of 1944, which made it possible to break the Luftwaffe over the Reich. The division of labour that chronologies attribute to 6 October 1942 thus became reality, but not by virtue of a single agreement – rather as the outcome of a months-long dispute, the compromise at Casablanca and the costly experience of both air forces.