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 Nazi's. 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 attack just four days before German's unconditional surrender.

It's hard to imagine the destruction the world might have seen had the Nazis had access to nuclear weapons, in 1943 this seemed like a real possibility. Nestled in the Norwegian hillside was a facility that could provide the Nazis with another piece to their nuclear puzzle: heavy water. Vemork Hydro Plant had a giant store and the ability to produce more. With the threat of the nuclear weapons looming, the Allies would plan and carry out Operation Gunnerside, the most successful act of sabotage in WWII. A daring mission to thwart Hitler's atomic bomb. It would require skis, scaling equipment and explosives and the sacrifice of many brave men.