Thiel had been an associate professor of engineering at the Institute of Technology in Darmstadt before joining Wernher von Braun's team at the Army Research Center Peenemünde, where he was involved in developing the V-2 rocket. By the end of the war, he was transferred to the United States by the US Army (see Operation Paperclip and German rocket scientists in the US) where he resumed his work with von Braun's group in Fort Bliss, Texas. During the nine years Thiel worked for the U.S. Army, he held positions at White Sands Missile Range in New Mexico and at Huntsville, Alabama. He primarily supervised preliminary design of the Redstone missile and other short- and intermediate-range ballistic missile systems.