Helmut Rosenbaum was born on 11 May 1913 in Döbeln, and entered the Reichsmarine on 15 August 1932 (Crew 1932).

Helmut Rosenbaum on board U-35, summer 1937.

He was assigned to U-35 and U-27 as a watch officer in summer 1937.

Between 15 June and 09 October 1938, he was First Watch Officer on U-31.

He was First Watch Officer of U-26 between 06 November 1938 and 16 March 1939.

He was given command of U-2 on 17 March 1939 until 05 August 1940, and commanded U-73 between 30 September 1940 and 30 September 1942. He was awarded the Iron Cross 1st Class on 25 April 1941, and the Knight's Cross on 12 August 1942.

On 01 October 1942, he became chief of the 30th U-Flotilla in Kostanza and was killed on 10 May 1944 in an airplane crash in Rumania. He was promoted to Korvettenkapitän upon his death.