Werner Hartmann spent the first years of his career as commander of the torpedo boats Seeadler and Albatros. In 1935 he transferred to the U-boat arm and remained there through the end of World War II. With his first U-boat, U-26, he patrolled in Spanish waters during the Spanish Civil War in 1937-38. I WO on board was the later famous Oberleutnant z. S. Günther Prien.