Complex sentence: After some months he was given command of 3rd U-boat Flotilla, but in August 1941 returned to the staff of the Befehlshaber der U-boote.
Split into simpler sentences: After some months he was given command of 3. Unterseebootsflotille, but in August 1941 returned to the staff of the Befehlshaber der U-boote.