The Bombing War: Europe 1939-1945

The most difficult problem confronting airmen after 1919 was the unstable and rapidly evolving nature of the air weapon. The gap between the biplanes and triplanes of 1918 – slow, cumbersome, easily damaged craft made of wood and wire – and the faster monoplane, metal-framed and heavily armed aircraft of 1939, was a quantum leap in technology. It was essential, given limited budgets and little practical experience, that right choices be made when modernizing an air force. Since the technology changed almost year by year, overcommitment to a particular aircraft model or strategic profile could prove costly; with such a potentially unstable technology, obsolescence was a high risk and security uncertain. This was no more evident than in the shifting balance between offensive and defensive air power. By the late 1920s light bombers were as fast, or faster, than the biplane fighters that might intercept them; by the late 1930s high-performance monoplane fighters were more than 100 miles per hour faster than the light and medium bombers they opposed, capable of much greater manoeuvrability and with powerfully destructive armament. In almost all major European states radar detection of incoming enemy aircraft was either operationally available or in the process of development. As the balance shifted towards defence, air forces had to choose carefully the kind of bomber aircraft they should now invest in. This perhaps explains the designation of ‘Ideal Bomber’ given by the RAF when it began to search in 1938 for a heavy aircraft (specification B19/38), capable of long range, a heavy bombload, and flying high enough and fast enough to be less troubled by enemy fighter aircraft.⁷⁸ In the end, the project remained idealistic: the bombers that the RAF relied on for its later offensive were twin-engine bombers hastily converted to a multi-engine heavy-bomber role in the first years of war.

Most air forces between the wars opted to develop battlefield light- and medium-bomber aircraft, supported by ground-attack fighter-bombers, rather than pursue the strategic aim of the ‘knockout blow’. This was true even in Douhet’s Italy, where the air force rejected mass fleets of bombers in favour of a variety of assault aircraft to support surface operations.⁷⁹ This choice depended to some extent on the prevailing role of the army in overall military planning and the army’s belief that the most strategically efficient use of air power was in some form of combined arms operational structure. In France, Germany and the Soviet Union there existed a core of airmen who did favour an independent strategic air force, based around a bombing capability, but they lacked sufficient prestige or influence to overcome the preference of the ground army to exploit air power as an important adjunct to any ground campaign or the opposition of those airmen who thought air defence and air-to-air combat a better use of scarce resources.

In France, the armed forces were strongly influenced by the experience of the Great War, which seemed to demonstrate clearly that overwhelming air power on or near the fighting fronts was more strategically decisive than speculative long-range bombing of the enemy home front. The main statement of French bombing theory by Camille Rougeron, L’Aviation de Bombardement, argued that the ideal bomber aircraft should be derived from fighter design and be used both to attack military targets and to win air superiority over the battlefield.⁸⁰ The 1921 French Instruction for the armed forces laid down the principle that air power should be used in support of front-line operations. In 1936 the Instruction was modified by the Popular Front Air Minister, the radical left-wing politician Pierre Cot, to allow for the creation of an operationally independent strategic reserve. But even this reserve was designed to allow for mass attacks at critical points in the battle either to disrupt enemy supplies and reinforcements or to make possible a breakthrough on the ground. When Cot lost office in 1938, the strategic reserve was once again broken up and distributed among the defending armies along the French eastern frontier.⁸¹ The French Army deeply distrusted Cot and his sympathy for the Soviet Union and came to identify his policy of independent, strategic air power as a Communist attempt to subvert the role of the army in determining French military doctrine. The ‘strategic’ use of air power was regarded as simply an extension of the main battle, not as an alternative.