10 April 1941, the Siege of Tobruk began.

Over the next 242 days, Australian, British, Indian and Polish troops, supported by RN and RAN and merchant ships defended the Fortress of Tobruk against German and Italian forces attempting to overrun the strategically important port. Access to it would provide a much more direct re supply of Axis forces aiming to take Egypt and seize the Suez Canal.

Crucial to the success of the defence was the support from the Tobruk Ferry Service from the RN Fleet Base at Alexandria. This included Australian destroyers.

In the face of threats from air, surface and submarine attack, eight RAN destroyers made almost 140 voyages to Tobruk, providing gunfire support, escorting and delivering stores, food and ammunition and evacuating the wounded. HMAS Vendetta made over 30 individual supply runs.

Both HMAS Waterhen and HMAS Parramatta were sunk while on these hazardous duties, the latter with heavy loss of life.