Sparrow Force was a detachment based on the 2/40th Australian Infantry Battalion and other Dutch, British, US and Australian 8th Division units during World War II. The force was formed to defend the island of Timor from invasion by the Empire of Japan. It formed the main part of the Allied units in the Battle of Timor. The force began deploying in late 1941, and following Japan's entry into the war, it was drawn into the fighting in response to the Japanese invasion of Portuguese and Dutch Timor in February 1942. After heavy fighting around Irekum, the main element of the force – the 2/40th – were forced to surrender on 23 February 1942; however, elements of the force, specifically commandos from the 2/2nd Independent Company, supported by the local population, continued a guerilla campaign and inflicted heavy casualties on the Japanese until August, when the Japanese launched a counter-offensive. Despite reinforcements from the 2/4th Independent Company arriving in September 1942, the Japanese offensive eventually resulted in the withdrawal of Allied troops over the period December 1942 to January 1943, with the commandos being withdrawn by sea. Sparrow Force personnel who were captured during the fighting were sent to Japanese labour camps across south-east Asia, and between 1942 and 1945, many died in captivity. Background In December 1941, due to concerns about a Japanese invasion, the Dutch requested that Australian forces be sent to both Koepang and Ambon under provisions that had been agreed to in a conference at Singapore earlier in the year. That plan, entitled "Plans for the employment of naval and air forces of the associated powers in the eastern theatre in the event of war with Japan" (Plenaps), had already resulted in the disposition of forces, including some U.S. fleet movements, as early as November 1941. Initially, Australian plans were to send forces only to Koepang with the resulting order to embark the force at Darwin, designated "Sparrow," on 7 December 1941 using the transport and the armed cruiser HMAS Westralia, which were available in the port. The decision to exclude Ambon was quickly changed with 1,090 troops designated "Gull Force" sent to Ambon from Darwin on 14 December using three Dutch merchant ships. In January 1942, the Allied forces on Timor became a key link in the so-called "Malay Barrier", defended by the short-lived American-British-Dutch-Australian Command under the overall command of General Sir Archibald Wavell.