Johannes "Hans" Klein was with ReichsprotektorReinhard Heydrich on May, 27, 1942, the day two Czech partisans attempted to assassinate Heydrich in Prague. Klein's steadfast demeanor and clear thinking impressed Heydrich, who kept Klein as his aid-de-campe. When Heydrich began preparing a resistance in the face of a possible Allied invasion of Germany in 1943, Klein became Heydrich's close confidant.
When the Allies did occupy Germany in 1945, Klein followed Heydrich into hiding in the Alpine Redoubt. Heydrich frequently shared ideas with Klein for further terrorizing the Allies. In 1946, Klein escorted Heydrich on one of the few missions the Reichprotektor personally oversaw--the kidnapping of several German scientists from British custody. He stayed with Heydrich until the bitter end, which came in 1947 when the United States Army finally located Heydrich's hideout. Heydrich was killed, but Klein survived, proudly acknowledging his role in assisting Heydrich.