The flotilla at first only consisted of U-9, a Type IIB boat commissioned on 21 August 1935. Later, boats U-1 to U-12 were included in the flotilla, but U-1 to U-6 were only used as training boats and were attached to the U-boat training school in Neustadt.[3] Originally based in Kiel from September 1935-May 1941, it was moved to Brest, France in June 1941.