Rettig was a villain appearing in The Rat Patrol.
Rettig was a ruthless Gestapo agent operating in the Spanish Sahara, a neutral zone in North Africa. He and his men captured Sam Troy after he'd received photographs of German installations, but he had hidden the photographs. Rettig beat Troy up, against the protests of Captain Hans Dietrich, who insisted Troy be treated as a prisoner of war and not a spy, and also expressed concern for the Germans' actions in a neutral zone.
Troy was eventually freed by his companions from the Rat Patrol. After learning that a boy named Tico had obtained the photographs, Rettig had Tico's sister Sarina captured and held prisoner, and forced him to lead him to where he was keeping the photos in exchange for Sarina's safe release. As soon as he obtained the pictures, he and the agent he'd brought with him were captured by the Rat Patrol. Troy offered them to Dietrich in exchange for Sarina's release. Although the deal went through, an enraged Rettig grabbed a rifle and shot at the retreating Allies, forcing Moffitt to shoot him.