Air Force Museum
75mm Cannon
During World War II, the AAF equipped its B-25G and B-25H medium bombers and some Douglas A-26B light bombers with a single-shot manually loaded 75mm cannon in the nose. Though only three of four rounds could be fired during a single attack run on a target, these aircraft caused considerable damage to enemy shipping and ground targets, particularly in the Pacific.
In depth
History & service
During World War II, the AAF equipped its B-25G and B-25H medium bombers and some Douglas A-26B light bombers with a single-shot manually loaded 75mm cannon in the nose. Though only three of four rounds could be fired during a single attack run on a target, these aircraft caused considerable damage to enemy shipping and ground targets, particularly in the Pacific. Although automatic feed mechanisms were designed to increase the rate of fire, the successful employment of aircraft rockets late in WWII halted further development of heavy aircraft cannon. But in the 1960s, the development of heavy rapid-fire cannon was resurrected for use in Southeast Asia and in other advanced ground attack applications.
Aircraft change the battlefield
In the First World War, aircraft became valuable because they could see beyond the front line. Reconnaissance and artillery observation affected decisions on the ground. Once that information mattered, opposing forces had reason to attack the aircraft gathering it. Fighters, defensive armament, and increasingly specialized missions developed around this contest over observation and freedom of movement.
The aircraft were fragile by later standards, but their crews worked inside a rapidly expanding military system. Training, maintenance, replacement aircraft, photography, communications, and weather reporting supported each sortie. Improvements in engines and armament changed tactics, while the pressures of combat exposed weaknesses that might have taken much longer to discover in peacetime.
Personal stories should be read alongside those systems. A uniform or a named aircraft connects the war to an individual, but the individual depended on many others and operated under constraints that skill could not eliminate. Aircraft from opposing sides show how designers answered similar problems in different ways. The later military collections in Dayton and at Udvar-Hazy reveal what endured: the need to gather information, protect friendly forces, move people and supplies, and coordinate action across distance. The scale changed enormously; the relationship between an aircraft's design and the job it had to perform remained fundamental.
