Siegfried Friedrich Heinrich Müller (26 October 1920 – 17 April 1983), referred to as "Congo Müller" (Kongo-Müller), was a German-born mercenary who served as an officer with 5 Commando during the Congo Crisis. A former officer-candidate in Nazi Germany's Wehrmacht who continued to wear his Iron Cross, Müller acquired particular notoriety in West and East Germany in the mid-1960s amid extensive press coverage of his involvement in war crimes in the Congo and overt nostalgia for the Nazi era. Siegfried Friedrich Heinrich Müller was born in Crossen an der Oder, Germany (modern Krosno Odrzańskie, Poland) in 1920 to a conservative Prussian family. His father served in World War I and later served in the Wehrmacht as a lieutenant-colonel. Siegfried was enrolled at a boarding school in Freiburg and was in the Jungvolk, reaching the rank of Fähnleinführer. He later served in the Reich Labour Service, and joined the Wehrmacht in 1939. He first experienced action during the German invasion of Poland, where he says he saw very little combat. After this, he claimed he would sometimes dress as a Polish peasant and walk along the lines of the Soviet-occupied Poland in order to scout them out. He also fought in Operation Barbarossa and spent the rest of the war fighting against the Soviets. He claimed to have been promoted to the rank of first lieutenant on April 20, 1945, Hitler's birthday. After being seriously wounded from being shot in the back, he was evacuated from East Prussia to Frankfurt, where he was captured by the Americans. Released in 1947, he enlisted in the US Army Civilian Labor Group (CLG), an American Labor Service Unit of Germans; then became a lieutenant in a CLG security unit. He also worked as an Industrial Police watchman and trained NATO troops in Paris. He was denied entry to the Bundeswehr in 1956, but found employment with British Petroleum, clearing mines planted by the Afrika Korps in the Sahara Desert during World War II.