From the WIA, original post here.

Date : 20 / 11 / 2016 
Author : Jim Linton – VK3PC

The 75th anniversary of the sinking of HMAS Sydney in the Indian Ocean is being remembered on by commemorative callsigns on both sides of Australia.  It was on November 19, 1941, that HMAS Sydney engaged in a naval battle with German auxilliary cruiser, SMS Kormoran, about 106 nautical miles off Dirk Hartog Island Western Australia.

The sinking of the Sydney in the half an hour fire fight remains the largest loss of life in the history of the Royal Australian Navy (RAN), with all 645 sailors perishing.  Most of the crew of Kormoran survived, captured and made prisoners of war until the conflict ended.  The wreckage sites were only verified in 2008.

To mark the occasion the St George Amateur Radio has VI2SYD75 is active on HF through VHF, and even microwaves, while the Northern Corridor Radio Group has VI6SYD75 initially at HMAS Sterling base at Garden Island, before relocating to at least two other locations.  There have been four Royal Australian Navy ship named HMAS Sydney.  The first commissioned in 1912 gained fame through an action with the German light cruiser SMS Emden off the Cocos-Keeling Islands on November 9, 1914.  It was the first Australian naval action of WWI.  The Emden was beached on North Keeling Island, one of the Cocos-Keeling Islands group in the Indian Ocean.  The callsign VI4SEA commemorated that event, coordinated by Mike Charteris VK4QS.

The second HMAS Sydney was commissioned in 1934, and is the one lost in 1941.  The 3rd was an aircraft carrier used during the Vietnam War to transport men and equipment.  This was fondly known as “The Vung Tau Ferry.”  The 4th HMAS Sydney was commissioned in 1983 and remained in service until 2015.