In December of that year, now operating in the Central Mediterranean, Vasilissa Olga and a British destroyer briefly captured an Italian submarine, but it sank while under tow.

During her sea trials on 19 December 1938, Vasilissa Olga reached a speed of 36.1 knots (66.9 km/h; 41.5 mph) from 33,683 shp (25,117 kW), although her armament was not yet installed.

[2] During her late 1941 refit in Calcutta, India, Vasilissa Olga's armament was revised to better suit her role as a convoy escort.

During the Greco-Italian War she escorted convoys and participated in raids against Italian lines of communication in the Strait of Otranto on the nights of 14/15 November 1940 and 4/5 January 1941 that failed to locate any ships.

[6] The refit was completed on 5 January 1942 and the ship escorted convoys in the Arabian and Red Seas before arriving back in Alexandria on 22 February.

Together with the British destroyer HMS Jaguar, Vasilissa Olga was escorting the oil tanker RFA Slavol off Mersa Matruh, Egypt, when they detected and unsuccessfully attacked the German submarine U-652 on 26 March.

[4][7] On 14 December, Vasilissa Olga and the destroyer HMS Petard forced the Italian submarine Uarsciek to the surface off Malta.

The following month, the ship was assigned to escort the ocean liners transporting the Australian Army's 9th Division home from Egypt (Operation Pamphlet) as they passed through the Red Sea between 7 and 24 February.

[9] On 2 June, during the preparatory stages of Operation Corkscrew (the Allied invasion of the Italian island of Pantelleria), Vasilissa Olga and the destroyer HMS Jervis fought the Battle of the Messina Convoy, sinking its lone escort, the torpedo boat Castore off Cape Spartivento.

[10][11] The ship was transferred to the Eastern Mediterranean to support British forces involved in the Dodecanese Campaign in the Aegean Sea less than a week later, arriving at Alexandria on 16 September.

Vasilissa Olga transported 36 long tons (37 t) of supplies and 300 men of the Queen's Own Royal West Kent Regiment from Haifa, Palestine, to reinforce the British garrison on Leros.