On April 18, 1942, 16 Army B-25 bombers took off from the Navy aircraft carrier USS Hornet to bomb Japan. None of the pilots, including the raid’s leader, Jimmy Doolittle, had ever taken off from a carrier before. The idea came from a Navy officer, Captain Francis Low.
The bombers were changed for a job they were not built for. Their fuel capacity was raised from 646 to about 1,141 gallons. Broomsticks painted black were mounted in the tail to look like guns. The secret Norden bombsight was replaced with a makeshift sight devised by pilot Ross Greening, described as a “20 cent aluminum version.” The crews trained for three weeks in short takeoffs that simulated a carrier deck.