Sparrow Force was initially commanded by Lieutenant Colonel William Leggatt, and included the 2/40th Battalion, a commando unit—the 2nd Independent Company—under Major Alexander Spence, and a battery of coastal artillery. There were in total around 1,400 men. The force reinforced Royal Netherlands East Indies Army troops under the command of Lieutenant Colonel Nico van Straten, including the Timor and Dependencies Garrison Battalion, a company from the VIII Infantry Battalion, a reserve infantry company, a machine-gun platoon from the XIII Infantry Battalion and an artillery battery. Air support consisted of 12 Lockheed Hudson light bombers of No. 2 Squadron, Royal Australian Air Force (RAAF). Sparrow Force was initially deployed around Kupang, and the strategic airfield of Penfui in the south-west corner of the island, although other units were based at Klapalima, Usapa Besar and Babau, while a supply base was also established further east at Champlong.