The Battle of Timor occurred in Portuguese Timor and Dutch Timor during the Second World War. Japanese forces invaded the island on 20 February 1942 and were resisted by a small, under-equipped force of Allied military personnel—known as Sparrow Force—predominantly from Australia, United Kingdom, and the Dutch East Indies. Following a brief but stout resistance, the Japanese succeeded in forcing the surrender of the bulk of the Allied force after three days of fighting, although several hundred Australian commandos continued to wage an unconventional raiding campaign. They were resupplied by aircraft and vessels, based mostly in Darwin, Australia, about 650 km (400 mi) to the southeast, across the Timor Sea. During the subsequent fighting, the Japanese suffered heavy casualties, but they w