Heinz Guderian (1888–1954) German general
Letter to his wife (9 November 1941) on the German failures in Operation Barbarossa and the battles of the Eastern Front, quoted in Images of Kursk : History's Greatest Tank Battle, July 1943 (2002) by Nikolas Cornish, p. 6; also in The Storm of War: A New History of the Second World War (2009) by Andrew Roberts, p. 409