Originally designed as a yacht and despatch vessel for the Italian Head of Government, she was converted for military use.

Diana was laid down on 31 May 1939 at the Cantieri Navali del Quarnaro in Fiume, launched on 20 May 1940 and completed on 12 November 1940.

[1] The ship left Messina, Italy on 28 June 1942 to bring material and personnel to Tobruk, a city recently reconquered by the Axis forces.

In what he described as his "most satisfactory patrol" in the Mediterranean, in June 1942, Sir Hugh Mackenzie, Commander of the British submarine HMS Thrasher, reported that on their way back to Alexandria, north of Tobruk, they received a signal about an Axis ship which was due in the area at 12 O'clock on the following day and that it was vitally important to sink it (presumed to be Diana).

Later, between 29 and 30 June, the hospital ship Arno arrived, which took care, albeit in rough seas, of the recovery of the 119 survivors; 336 members of the crew had been killed.