HMS SILVIO was one of four World War I Royal Navy Minesweepers converted to Survey Ships in 1922-25. Sister ships were Iroquois, Ormonde and Herald.
In 1925 Silvio was lent to the Australian Commonwealth Government to assist in the survey of the Cumberland Channel inside the Great Barrier Reef off the Queensland coast. Before leaving England for Australia in June 1925, she commissioned in the Royal Australian Navy and was renamed Moresby in honour of Admiral John Moresby who had discovered Port Moresby (New Guinea) in HMS Basilisk on 21st February, 1873. Admiral Moresby died in July 1922, at the age of 92.
HMAS Moresby reached Australia in September 1925, under the command of Captain J.A. Edgell RN, who later as Vice- Admiral Sir John Edgell, KBE, became Hydrographer to the Admiralty. She was engaged on the Barrier Reef survey, assisted until 1927, by HMAS Geranium, until December 1929, when, for reasons of economy she was paid off at Sydney on 21st December.
On 27th April 1933 Moresby was recommissioned for urgent strategic survey work in Australian northern waters. Excepting for four months (December 1934 – April 1935) when she was placed in Reserve, she was engaged on this task continually up to the outbreak of World War II in 1939.
For the first year of the war Moresby served as an Anti-Submarine training vessel. In January 1941, she resumed her former duty as a Survey Vessel and until the outbreak of war with Japan in December 1941, was engaged in surveying Australian and New Guinea waters.
In January 1942, Moresby was assigned to duty as an Escort and Anti-Submarine vessel in Australian waters and until the end of 1943 was almost constantly at sea escorting convoys moving along the Australian east coast. This was the period when Japanese submarines were active in Australian coastal waters, and three attacks were made on ships under escort by Moresby.
In December 1942, off Gabo Island, a submarine fired a torpedo at the SS Kooyong but it passed harmlessly under her keel. A second attack took place in April 1943, and resulted in the sinking of the Yugoslav vessel Recina with the loss of 32 lives. A month later off the New South Wales coast the Ormiston was torpedoed but made port under her own steam. In all during the period Moresby was serving as an Escort Vessel nineteen ships were sunk off the Australian coast by Japanese submarines with the loss of 568 lives.
In November 1943, Moresby ceased operating as an Escort Vessel and at Sydney prepared to resume duty as a Survey Vessel. From December 1943 until the end of the war she was engaged on surveys mainly in the Darwin and Bathurst Island areas. In September – October, 1945 she took part in the re-occupation of Timor and was present at the surrender ceremony on 11th September 1945. In November 1945, she carried out a survey of Yampi Sound (West Australia) before returning to Sydney, where she arrived on 13th December 1945. She paid off on 14th March 1946, and was sold for breaking up to Broken Hill Co. Ltd., on 3rd February 1947.