Australia Station and Australian defences
The definition of "Australian waters" used throughout this article is, broadly speaking, the area which was designated the
Australia Station prior to the outbreak of war. This vast area consisted of the waters around Australia and eastern
New Guinea, and stretching south to
Antarctica. From east to west, it stretched from
170° east in the
Pacific Ocean to
80° east in the
Indian Ocean, and from north to south it stretched from the
Equator to the Antarctic.
 While the eastern half of New Guinea was an Australian colonial possession during the Second World War and fell within the Australia Station, the Japanese operations in these waters formed part of the
New Guinea and
Solomon Islands Campaigns and were not directed at Australia.
Two merchant navy seamen standing in front of a gun fitted to their ship
The defence of the Australia Station was the
Royal Australian Navy's main concern throughout the war.
 While RAN ships frequently served outside Australian waters, escort vessels and
minesweepers were available to protect shipping in the Australia Station at all times. These escorts were supported by a small number of larger warships, such as
armed merchant cruisers, for protection against surface raiders.
 While important military shipping movements were escorted from the start of the war,
convoys were not instituted in Australian waters until June 1942. The Australian naval authorities did, however, close ports to shipping at various times following real or suspected sightings of enemy warships or mines prior to June 1942.
Royal Australian Air Force (RAAF) was also responsible for the protection of shipping within the Australia Station.
 Throughout the war, RAAF aircraft escorted convoys and conducted reconnaissance and anti-submarine patrols from bases around Australia. The main types of aircraft
maritime patrol were
Consolidated PBY Catalinas and
Lockheed Hudsons. Following the outbreak of the
Pacific War, RAAF fighter squadrons were also stationed to protect key Australian ports and escorted shipping in areas where air attack was feared.
The Allied naval forces assigned to the Australia Station were considerably increased following Japan's entry into the war and the beginning of the
United States military build-up in Australia. These naval forces were supported by a large increase in the RAAF's
maritime patrol force and the arrival of
United States Navy patrol aircraft. Following the initial Japanese submarine attacks, a convoy system was instituted between Australian ports, and by the end of the war the RAAF and RAN had escorted over 1,100 convoys along the Australian coastline.
 As the battlefront moved to the north and attacks in Australian waters became less frequent, the number of ships and aircraft assigned to shipping protection duties within the Australia Station was considerably reduced.
In addition to the air and naval forces assigned to protect shipping in Australian waters, fixed defences were constructed to protect the major Australian ports. The
Australian Army was responsible for developing and manning
coastal defences to protect ports from attacks by enemy surface raiders. These defences commonly consisted of a number of fixed guns defended by anti-aircraft guns and infantry.
 The Army's coastal defences were considerably expanded as the threat to Australia increased between 1940 and 1942, and reached their peak strength in 1944.
 The Royal Australian Navy was responsible for developing and manning harbour defences in Australia's main ports.
 These defences consisted of fixed anti-submarine booms and mines supported by small patrol craft, and were also greatly expanded as the threat to Australia increased.
 The RAN also laid defensive minefields in Australian waters from August 1941.
While the naval and air forces available for the protection of shipping in Australian waters were never adequate to defeat a heavy or coordinated attack, they proved sufficient to mount defensive patrols against the sporadic and generally cautious attacks mounted by the Axis navies during the war.