There was considerable Axis naval activity in Australian waters during the Second World War, despite Australia being remote from the main battlefronts. 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. About 40 Allied merchant ships were damaged or sunk off the Australian coast by surface raiders, submarines and mines. Japanese submarines also shelled three 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
The maritime approaches to Australia were 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.
The defence of the Australia Station was the Royal Australian Navy's (RAN) main concern throughout the war. Although 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. Important military shipping movements were escorted from the start of the war, but 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.
The 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 used for maritime patrol were Avro Ansons, Bristol Beauforts, Consolidated PBY Catalinas and Lockheed Hudsons. Ansons were the main type available during the first years of the war, but were not well suited to this task due to their short range and modest weapon-carrying capacity. The introduction of Beauforts and Hudsons considerably improved the RAAF's maritime patrol and anti-submarine capacities. A network of airfields along the Australian coastline was established over the course of the war to support the RAAF's maritime patrol operations. Anti-submarine work required intensive efforts by the RAAF aircrew. For instance, aircraft needed to sweep the entrance to harbours before convoys departed and then constantly patrol over them while they were at sea.
The Allied naval forces assigned to the Australia Station were considerably increased following Japan's entry into the war in December 1941 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 (USN) 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 in 1944. The RAN 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.
The cargo ships that operated in Australian waters during World War II were mostly crewed by civilians, with the Australian vessels and their crews being organised loosely as the Australian Merchant Navy. These sailors endured considerable risks in the course of their employment. Most of the cargo ships were unarmed, though some were fitted with guns. The guns on the ships that were armed were operated by Defensively Equipped Merchant Ship personnel provided by the RAN and members of the ship's crew. Merchant seaman received war risk bonuses that were increased over the course of the war as a result of advocacy from unions. This led to them receiving approximately equal pay and allowances to members of the RAN. A 1989 inquiry undertaken by the Repatriation Commission found that merchant mariners were exposed to greater risks than many members of the RAN as they more frequently operated in dangerous waters and their ships were not designed to survive attacks. The support provided to civilian mariners who survived the loss of their ship during the war was also generally inferior to that provided to naval personnel.
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.
1939–1941
German surface raiders in 1940 German surface raiders operated in the western Indian Ocean in 1939 and early 1940, and began to enter Australian waters in second half of 1940. The German surface raider was the first Axis warship to operate in Australian waters during World War II. After operating off the northern tip of New Zealand and the South Pacific, Orion entered Australian waters in the Coral Sea in August 1940 and reached a point north-east of Brisbane on 11 August. She then headed east and operated off New Caledonia before proceeding south into the Tasman Sea, sinking the merchant ship Notou south-west of Noumea on 16 August and the British merchant ship Turakina in the Tasman Sea four days later. Orion sailed south-west after sinking Turakina, passing south of Tasmania, and operated without success in the Great Australian Bight in early September. Orion laid four dummy mines off Albany, Western Australia on 2 September and departed to the south-west after being spotted by an Australian aircraft the next day. After unsuccessfully patrolling in the Southern Ocean, Orion sailed for the Japanese-controlled Marshall Islands to refuel, arriving there on 10 October.
was the next raider to enter Australian waters. She entered the Indian Ocean from the South Atlantic in August 1940 and arrived off Western Australia in October. On 7 October Pinguin captured the Norwegian tanker Storstad which was sailing from Borneo to Melbourne. A German prize crew took over Storstad and mines were transferred to her from Pinguin. The two ships then sailed to the east. Pinguin laid mines off the New South Wales coast between Sydney and Newcastle on the night of 28 October, with the two vessels then departing for Tasmanian waters. Pinguin laid two minefields off Hobart on 31 October and 1 November, and over the period 29–31 October Storstad laid mines in Banks Strait off the north-east corner of Tasmania and off Wilson's Promontory and Cape Otway on the Victorian coast. Pinguin also laid further mines in Spencer Gulf off Adelaide in South Australia in the first week of November. The two ships then sailed west for the Indian Ocean. Pinguin and Storstad were not detected during their operations off Australia's eastern and southern coasts. Mines laid by Storstad sank the cargo ship Cambridge off Wilsons Promontory and the American City of Rayville off Cape Otway on 8 and 9 November, and the mines laid off Sydney by Pinguin sank the coastal steamer Nimbin. The British steamer Hertford was also damaged after striking a mine at the entrance to Spencer Gulf. Pinguin sank another three merchant ships in the Indian Ocean during November.
On 7 December 1940, the German raiders Orion and arrived off the Australian protectorate of Nauru. During the next 48 hours, they sank four merchant ships. Heavily loaded with survivors from their victims, the raiders departed for Emirau Island where they unloaded the prisoners. After an unsuccessful attempt to lay mines off Rabaul on 24 December, Komet made a second attack on Nauru on 27 December and shelled the island's phosphate plant and dock facilities. This was the last Axis naval attack in Australian waters until November 1941.
The raid on Nauru led to serious concerns in Australia about the supply of phosphates from there and nearby Ocean Island, though the lack of availability of warships allowed only limited response to threats to the isolated islands. Some warships were redeployed, and it was decided to install six-inch naval guns on the islands despite provisions of the mandate prohibiting fortifications. Due to shortages of these guns the intended defences were reduced to two field guns for each island. The most serious effect of the raid was the fall in phosphate output, though decisions made as early as 1938 to increase stockpiles of raw rock in Australia mitigated the decline. Another consequence was the institution of the first Trans-Tasman commercial convoys, with Convoy VK.1 composed of , , Empress of Russia, and Maunganui leaving Sydney 30 December 1940 for Auckland escorted by the light cruiser .
German surface raiders in 1941