"Unmöglich." Impossible. That was the word echoing through German High Command bunkers on December 19, 1944. American General George S. Patton had just announced he would pivot three full divisions ninety degrees, march them through the worst winter in decades, and attack the southern flank of Germany's Ardennes Offensive—in just 48 hours.

German Field Marshals laughed. Intelligence officers dismissed it as propaganda. Hitler himself declared no army could accomplish such a maneuver in less than a week. 
They were all spectacularly wrong.