Axis naval activity in Australian waters

A propaganda poster calling on Australians to avenge the sinking of the Australian hospital ship Centaur by the Japanese submarine I-177 in May 1943.

Although Australia was remote from the main battlefronts, there was considerable Axis naval activity in Australian waters during the Second World War. A total of 54 German and Japanese warships and submarines entered Australian waters between 1940 and 1945 and attacked ships, ports and other targets. Among the best-known attacks are the sinking of HMAS Sydney by a German raider in November 1941, the bombing of Darwin by Japanese naval aircraft in February 1942, and the Japanese midget submarine attack on Sydney Harbour in May 1942. In addition, many Allied merchant ships were damaged or sunk off the Australian coast by submarines and mines. Japanese submarines also shelled several Australian ports and submarine-based aircraft flew over several Australian capital cities.

The Axis threat to Australia developed gradually and until 1942 was limited to sporadic attacks by German armed merchantmen. The level of Axis naval activity peaked in the first half of 1942 when Japanese submarines conducted anti-shipping patrols off Australia's coast, and Japanese naval aviation attacked several towns in northern Australia. The Japanese submarine offensive against Australia was renewed in the first half of 1943 but was broken off as the Allies pushed the Japanese onto the defensive. Few Axis naval vessels operated in Australian waters in 1944 and 1945, and those that did had only a limited impact.

Due to the episodic nature of the Axis attacks and the relatively small number of ships and submarines committed, Germany and Japan were not successful in disrupting Australian shipping. While the Allies were forced to deploy substantial assets to defend shipping in Australian waters, this did not have a significant impact on the Australian war effort or American-led operations in the South West Pacific Area.

Australia Station and Australian defences

A Bathurst-class corvette. This class of ship was commonly used to escort convoys in Australian waters.

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. [1] 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. [2] 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 cruisers and armed merchant cruisers, for protection against surface raiders. [3] 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.

A troop convoy escorted by a RAAF Lockheed Hudson aircraft

The Royal Australian Air Force (RAAF) was also responsible for the protection of shipping within the Australia Station. [4] Throughout the war, RAAF aircraft escorted convoys and conducted reconnaissance and anti-submarine patrols from bases around Australia. The main types of aircraft used for maritime patrol were Avro Ansons, Bristol Beauforts, 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. [5] 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. [6]

Drummond Battery coastal defence gun emplacement near Port Kembla in 1944

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. [7] 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. [8] The Royal Australian Navy was responsible for developing and manning harbour defences in Australia's main ports. [9] 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. [10] The RAN also laid defensive minefields in Australian waters from August 1941. [11]

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. [12]