Dismayed by accusations of German atrocities, he published an angry defence of German military conduct in a popular book entitled Die Wahrheit über die deutschen Kriegsverbrechen (The Truth about German War Crimes) (1921). Promoted to the rank Generalleutnant (lieutenant general) in 1931, Stülpnagel played a leading role in the Reichswehr in conjunction with Kurt von Schleicher and Freiherr von Bussche during the Weimar era. Transferred to the fledgling Luftwaffe in 1934, Stülpnagel eventually took charge of the air force academy before falling from favour and retiring in March 1939.