The Battle of Castle Itter was fought on 5 May 1945, in the Austrian village of Itter in the North Tyrol region of the country, during the last days of the European Theater of World War II.
Troops of the 23rd Tank Battalion of the 12th Armored Division of the US XXI Corps led by Lieut. John C. "Jack" Lee, Jr., a number of Wehrmacht soldiers led by Major Josef "Sepp" Gangl, SS-Hauptsturmführer Kurt-Siegfried Schrader, and recently freed French prisoners of war defended Castle Itter against an attacking force from the 17th SS Panzergrenadier Division until relief from the American 142nd Infantry Regiment of the 36th Division of XXI Corps arrived.
The French prisoners included former prime ministers, generals, tennis star Jean Borotra, and Charles de Gaulle's sister. It is one of two known times during the war in which Americans and Germans fought side by side, the other being Operation Cowboy and the only known time where an active member of the Waffen SS fought on the Allied side. Popular accounts of the battle have called it the strangest battle of World War II.