Winston S. Churchill book The Second World War
To his personal secretary John Colville the evening before Operation Barbarossa, the German invasion of the Soviet Union. As quoted by Andrew Nagorski in The Greatest Battle (2007), Simon & Schuster, pp. 150–151 ISBN 0743281101
The Second World War (1939–1945)
Variant: If Hitler invaded Hell, I would make at least a favourable reference to the devil in the House of Commons.