Underground

On the Hogan's Heroes television series, the Underground is the name given to the German resistance movement to the Nazis. In the TV series, the Underground would assist Colonel Hogan's men and the Allies in general by collecting military intelligence, rescuing Allied pilots, spying on the Nazi German military and sabotaging the German war effort.

The Underground is mainly made up of ordinary Germans who do not agree with the policies of the Nazi regime, but also include certain members of the elite and the military, especially towards the end of the war when they realize that the war is lost.

Reality
Widerstand (German: 'resistance') is the general name given to the resistance movements inside Nazi Germany both before and during World War II.

Among the groups involved in the German resistance were the Swing Kids, the Edelweiss Pirates, the Red Orchestra, Operation Spark, the White Rose, the Kreisau Circle, and the July 20 Plot.

From 1938 to 1945, there were 17 assassination attempts against Adolf Hitler by the German Resistance.

The last assassination attempt against Hitler, called the July 20 Plot, resulted in the capture and executions of more than 4,800 known or suspected opponents of his regime, effectively destroying the resistance movement.