Although Germany flew the first helicopter (Focke-Wulf Fw 61) in 1936, extensive bombing by the Allies prevented mass production during WWII.

131 American Sikorsky R-4 helicopters saw service in World War II, primarily  for rescue in Burma, Alaska, and other areas with harsh terrain. By the end of World War II, Sikorsky had produced over 400 helicopters.

In 1941 the Imperial Japanese Army developed the Kayaba Ka-1 autogyro for reconnaissance, artillery-spotting, and anti-submarine uses. About 240 Japanese helicopters were produced throughout WWII.