To support naval operations in the Atlantic Ocean, the German Navy ran trials with various vessels in the 1920s and early 1930s.

As it was probable that the ships were underway for an extended time, the range was 12,500 NM (23,200 km) at 15 kn (28 km/h; 17 mph).

[1] The ship was laid down at the Schichau-Werke shipyard in Elbing East Prussia (now Elbląg, Poland) on 14 November 1936,[2] and was launched on 5 October 1937 with the name Westerwald.

[2] She arrived at Rosyth on 8 August 1945 and the following month went to Hebburn-on-Tyne for survey and repairs and conversion for service with the British Pacific Fleet, but the war ended and she was placed in reserve instead.

She therefore never served as an RFA, but was refitted for service in 1947 and on completion was renamed HMS Bulawayo in July 1947.