WWII: number of cannons and machine guns mounted on combat aircraft 1939-1945

During the First World War, planes were initially used for reconnaissance and observation, and the first aerial combat between powers was done by pilots throwing grenades or shooting pistols from the cockpit. Eventually, machine guns were mounted or integrated into the aircraft, but it was not until the interwar period and Second World War where the potential of aerial warfare was realized.

Aerial combat in the Second World War was fought on a scale never seen before. Aerial warfare was present in all theaters of war, and involved large scale bombing campaigns, support of ground and sea units, and battles in the air. While bombs caused the largest level of destruction, fighter planes were mounted with cannons and machine guns to shoot down enemy planes and provide assistance to ground assaults. Bombers were also mounted with defensive weapons to protect themselves from enemy attacks, and the size of heavy bombers allowed them to carry significantly more weapons than fighter planes.