S1, E2: The Battle of Castle Itter is the strangest WWII battle the world has never heard of, and the only battle where the Allies joined forces with the Germans to defeat the Nazis. High up in the Austrian Alps, an 18th-century castle housed some of Nazi Germany's most important political prisoners. Here, a ragtag band of former prime ministers, German defectors, and American infantrymen fought off SS attacks just four days before German's unconditional surrender.