Birth of Strategic Bombing

Strategic bombing first occurred during World War I when belligerents on both sides used rigid airships and heavy aircraft to deliver bombs on enemy targets far behind the front lines. Given the technology of the time, air strikes were few in number, inaccurate, and had a minor military impact. The psychological impact, however, was disproportionately large. The reaction of the public and workforce was immediate, as evidenced by factory absentee rates, the numbers of people fleeing cities for the countryside, and the clamor for government action. This strong reaction was caused by the novelty of the air weapon, not by its accuracy or destructiveness.

This belief in the psychological effects of strategic bombing strongly affected the public, governments, and military leaders during the interwar period. The three leading air theorists of this era—Giulio Douhet (Italy),Hugh Trenchard (Britain), and William “Billy” Mitchell (United States)—all assumed such a psychological impact in their projections of future war. The irony of this belief was its implicit promise that the horrors of strategic bombing would be so great that resorting to war would be less likely. In short, early air theorists saw strategic bombing as a deterrent that would keep the peace.

If deterrence failed, however, airmen hoped that strategic bombing would offer an antidote to the trench-warfare carnage of World War I. Strategic bombing, so the argument went, could bypass the tactical battle and strike directly at the “vital centers” of an enemy country. Strategic bombing, in conjunction with surface operations, would quickly bring victory. The intended targets of the bomber offensive were the industrial, economic, transportation, and government centers of the enemy. Note that it was the objective that determined whether a target was strategic or tactical, not the aircraft or weapon being used. Douhet—but not Trenchard and Mitchell—also called for direct attack on the population in the belief that their morale would break and they would demand an end to the war.

Strategic bombing during World War II was the sustained aerial attack on railways, harbors, cities, workers' housing, and industrial districts in enemy territory during World War II. Strategic bombing is a military strategy which is distinct from both close air support of ground forces and tactical air power.

During World War II, it was believed by many military strategists of air power that major victories could be won by attacking industrial and political infrastructure, rather than purely military targets. Strategic bombing often involved bombing areas inhabited by civilians and sometimes bombing campaigns were deliberately designed to target civilian populations in order to terrorize, disorganize, and disrupt their usual activities. International law at the outset of World War II did not specifically forbid aerial bombardment of cities despite the prior occurrence of such bombing during World War I, the Spanish Civil War, and the Second Sino-Japanese War.

Strategic bombing during World War II began on 1 September 1939 when Germany invaded Poland and the Luftwaffe (German air force) began bombing cities and the civilian population in Poland in an indiscriminate aerial bombardment campaign. As the war continued to expand, bombing by both the Axis and the Allies increased significantly. The RAF flew its first strategic bombing raid on Germany at Mönchengladbach on 11 May 1940 and in September 1940, the Luftwaffe began targeting British cities in 'The Blitz'. From 1942 onward, the British bombing campaign against Germany became less restrictive and increasingly targeted industrial sites and eventually, civilian areas. When the United States began flying bombing missions against Germany, it reinforced these efforts and controversial firebombings were carried out against Hamburg (1943), Dresden (1945), and other German cities.

In the Pacific War, the Japanese bombed civilian populations throughout the war (e.g. in Chongqing). The U.S. strategic bombing of the Japanese Empire began in earnest in October 1944 and escalated into widespread firebombing, which culminated in the atomic bombings of Hiroshima and Nagasaki on 6 and 9 August 1945 respectively, and the Japanese surrender on 15 August.

The effect of strategic bombing was highly debated during and after the war. Both the Luftwaffe and RAF failed to deliver a knockout blow by destroying enemy morale. However some argued that strategic bombing of military targets could significantly reduce enemy industrial capacity and production and in the opinion of its interwar period proponents, the surrender of Japan vindicated strategic bombing.

Japanese Home Islands Bombing

YB-29 Superfortresses in flight.

On May 14, 1945 472 B-29s attacked the area in and around the Mitsubishi engine factory at Nagoya. Two nights later, another visit to Nagoya devastated another four square miles of that city. On May 23 and May 25, Tokyo was hit again. Although these two Tokyo raids had cost 43 B-29s, over 50 percent of the city had now been destroyed.

Alarmed at the increasing B-29 losses, a change of tactics was ordered. In an attempt to confuse the enemy defenses and to lure Japanese fighters into an air battle in which many of them would be destroyed, high-altitude daylight attacks were temporarily resumed. On May 29, 454 B-29s appeared over Yokohama, but this time they were escorted by P-51 Mustangs from Iwo Jima. In the resulting dogfight, 26 Japanese fighters were destroyed against the loss of four B-29s and three P-51s. 

Thereafter, the Japanese hoarded their surviving fighters for a last-ditch effort against the inevitable invasion force, and the air defense of cities became a lesser priority. By June of 1945, Japanese interceptors were seen much less frequently and the B-29s had free reign over all Japanese airspace.

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Despite widespread awareness about the vulnerability of the Japanese home islands to air attack—reinforced by the results of the Doolittle Raid on Tokyo on 18 April 1942—U.S. plans for an air war against Japan remained vague until well into 1943 because of American limitations in resources and technology.

The development of the Boeing B-29 Superfortress changed this situation. Eventually, more than 1,000 of the long-range aircraft were deployed in the Twentieth Air Force under the direct control of the Army Air Forces commander, General Henry “Hap” Arnold, subdivided into the XX and XXI Bomber Commands. Under pressure to get results from his expensive very-heavy bomber program, he fielded the new aircraft even before testing had been completed.

In June 1944, B-29s from Major General Kenneth Wolfe’s XX Bomber Command began bombing Japan from China as part of Operation MATTERHORN. The campaign was plagued by logistical problems that got worse when Japanese troops overran advanced Allied airfields in China. Arnold replaced Wolfe with the USAAF’s premier problem-solver, Major General Curtis LeMay. However, even he could not make MATTERHORN a success. Arnold’s greatest hopes for an airpower victory over Japan rested with Brigadier General Haywood “Possum” Hansell’s XXI Bomber Command, which began operations from the Mariana Islands in November 1944. Hansell was one of the architects of the precision-bombing doctrine, but his operations also had little success.

Poor facilities, faulty training, engine failures, cloud cover, and jet streams at bombing altitudes made precision methods impossible. Hansell seemed unwilling to change his tactics, however, and Arnold feared that he would lose control of the heavy bombers to Allied Pacific theater commanders without better results, so he consolidated both bomber commands in the Marianas under LeMay and relieved Hansell.

LeMay instituted new training and maintenance procedures but still failed to achieve useful results with daylight high-altitude precision attacks. He decided to resort to low-level incendiary raids at night. Although area-firebombing went against dominant Air Forces doctrine, flying at low altitude reduced engine strain, required less fuel, improved bombing concentration, avoided high winds, and took advantage of weaknesses in Japanese defenses. LeMay’s systems analysts predicted that he could set large enough fires to leap firebreaks around important industrial objectives. His first application of the new tactics, Operation MEETINGHOUSE, against Tokyo on the night of 9 March 1945, produced spectacular destruction and was the deadliest air raid of the war.

Once enough incendiaries were stockpiled, the fire raids began in earnest. Warning leaflets were also dropped, which terrorized 8 million Japanese civilians into fleeing from cities. When General Carl Spaatz arrived in July to take command of U.S. Army Strategic Air Forces in the Pacific, including the Eighth Air Force redeploying from Europe, and to coordinate strategic air operations supporting the invasion of Japan, he had a directive to shift the air campaign from cities to transportation. But there was too much momentum behind the fire raids, sustained by operational tempo, training programs, and bomb stockage.

By the time Spaatz arrived, naval carrier strikes were also hitting key industrial objectives in Japan.More important, a submarine blockade had crippled the Japanese economy, the Russians were about to attack Manchuria, and Spaatz maintained direct command over the 509th Composite Group of B-29s specially modified to carry atomic bombs. Directed by Washington to deliver these weapons as soon as possible after 3 August, Spaatz ordered the attacks on Hiroshima and Nagasaki. These different elements combined with the incendiary campaign to comprise the series of blows that produced Japanese surrender.

As with the atomic bomb, there is still debate over the effects and morality of the firebombing raids. LeMay’s bombers burned out 180 square miles of 67 cities, killed at least 300,000 people, and wounded more than 400,000. His 313th Bomb Wing also sowed 12,000 mines in ports and waterways, sinking almost 1 million tons of shipping in about four months. LeMay remained convinced that his conventional bombing could have achieved victory by itself. LeMay, his tactics, and the legacy of the atomic bombs would be a primary influence in the shaping of the new United States Air Force.

References Hansell, Haywood S. Jr. Strategic Air War Against Japan. Washington, DC: U.S. Government Printing Office, 1980.