The Battle of the Coral Sea 4-8 May 1942

The first major naval battle in the Pacific Theatre of World War II.

This sea battle was the first naval action involving aircraft carriers, the first naval battle 'fought in the air', as well as the first in which neither side's ships sighted or fired directly upon the other.

Japanese forces had decided to invade and occupy Port Moresby in PNG. The plan to accomplish this, called Operation MO, involved several major units of Japan's Combined Fleet, including two fleet carriers and a light carrier to provide air cover for the invasion fleets.  The US learned of the Japanese plan through signal intellegence based in Austalia and sent two United States Navy carrier task forces and a joint Australian-American cruiser force, under the overall command of American Admiral Frank J Fletcher, to oppose the Japanese offensive.

HMAS Australia and HMAS Hobart, cruisers of the Royal Australian Navy, were part of the joint cruiser force.