THE REICH UNDERGROUND (2004) C

From Netflix:

This documentary is about the Third Reich's secret massive underground tunnel system. Most tunnels were designed to house armament factories that were being smashed (when they were above ground) by allied bombing. 

As the war ended, the tunnels were still being constructed by zillions of slave laborers deported from concentration camps. Most of the laborers died.
Depicts the absolute lunacy of the German regime and their complacent population.

Also describes the V2 missile effort led by Werner VonBraun. All of the missiles were manufactured in tunnels by slave laborers. HE HAD TO KNOW ABOUT IT. And then after the wars end, we welcomed him and his associates into the US of A so we could use his technology to enhance our military capability.

Wonderful, loving, feeling species . . . these homo sapiens.