In August 1933, he joined the Jungvolk, the junior section of the Hitler Youth. Trautmann joined the Luftwaffe early in the Second World War, and then served as a paratrooper. He served first in Occupied Poland. He fought on the Eastern Front for three years, earning five medals, including an Iron Cross. Later in the war, he was transferred to the Western Front, where he was captured by the British as the war drew to a close. As a volunteer soldier, he was classified a category "C" prisoner by the authorities, meaning he was regarded as a Nazi. One of only 90 of his original 1,000-man regiment to survive the war, he was transferred to a prisoner-of-war camp in Ashton-in-Makerfield, Lancashire. Trautmann refused an offer of repatriation, and following his release in 1948, settled in Lancashire, combining farm work with playing goalkeeper for a local football team, St Helens Town.