It had been agreed at the Second Four-Power Staff Conference in Singapore on 22.02.1941 that Australia would assume the defense of Timor and Ambon in case of war.
Units on Dutch Timor would be under Australian control, and those on Ambon under Dutch control.
Australian Army ground units quickly arrived at Koepang, Timor (Sparrow Force) on 12.12.1941,
and Ambon (Gull Force) on 17.12.1941, helped by the fact that advance parties and most of their supplies were already in place.
Artillery, vehicles, bombs, ammunition, aviation fuel, radios, and general stores had been prepositioned there during the proceeding months.
