The Butt Report, released on 18 August 1941, was a report prepared during World War II, revealing the widespread failure of RAF Bomber Command aircraft to hit their targets. At the start of the war, Bomber Command had no real means of determining the success of its operations. Crews would return with only their word as to the amount of damage caused or even if they had bombed the target. The Air Ministry demanded that a method of verifying these claims be developed and by 1941 cameras mounted under bombers, triggered by the bomb release, were being fitted.