Wojskowe Przyczyny Kleski Wrzesniowej (military reasons for the September defeat) One of two original copies of the Polish General Staff’s report on the causes of the German victory, presented to General Władyslaw Sikorski, Poland’s commander in chief, while he was in London, 1941. Wojskowe Przyczyny Klęski Wrześniowej Próba Syntezy typescript, Box 1, Hoover Institution Archives.