| Western Australian emergency of March 1944 | |
|---|---|
| Part of the Pacific theatre of World War II | |
 One of the anti-aircraft guns assigned to the defence of Fremantle in November 1943 | |
| Objective | Reinforcement of Western Australia in response to a feared Japanese attack |
| Date | 6–20 March 1944 |
| Outcome | No attack materialised, all units involved returned to their normal dispositions |
During March 1944, the Allies of World War II rapidly reinforced the military units located in the state of Western Australia to defend against the possibility that Japanese warships would attack the cities of Fremantle and Perth. This redeployment began on 8 March after concerns were raised about the purpose of Japanese warship movements near the Dutch East Indies, and ended on 20 March, after it was concluded that an attack was unlikely.
In February 1944, the Allies became alarmed that the movement of the main Japanese fleet to Singapore could be a precursor to raids in the Indian Ocean, including against Western Australia. The emergency began when Allied code breakers detected the movement of a powerful force of Japanese warships in the Netherlands East Indies in early March. After a United States Navy submarine made radar contact with two Japanese warships near one of the entrances to the Indian Ocean on 6 March, the Allied military authorities and Australian Government judged that a fleet may have been heading towards the Perth area. In reality, these warships were undertaking a patrol while awaiting a small raiding force to return from attacking ships in the central Indian Ocean.
In response to the perceived threat, the Allied military units stationed in Western Australia were placed on alert, and reinforcements were dispatched. These included six Royal Australian Air Force flying squadrons. Other Allied air units were held at Darwin in the Northern Territory to respond to raids on that town or reinforce Western Australia if the Japanese fleet was sighted. An air raid warning was sounded in Fremantle and Perth on 10 March, but this proved to be a false alarm. Intensive patrols by the Allied militaries did not detect any Japanese warships off Western Australia, and most units stood down on 12 March. On 20 March, it was concluded that the threat of attack had passed, and the air reinforcements that had been sent to Western Australia returned to their bases.