 Complete the following phrase:  On 1 January 1937 he was appointed Oberfähnrich zur See. After returning to Germany in February 1937, Maus took several technical courses. On 1 April 1937 he was promoted to Leutt zur See and returned to the cruiser Nürnberg, where he served as adjutant from 3 March 1939 to 14 June 1939 and was promoted to Oberleutt zur See on 1 April 1939. He was transferred to the battleship on 15 June 1939 and was present on the attacking battleship at the 