12 Squadron, which was equipped with CAC Wirraway advanced trainers (which had been pressed into service as fighters), and No. 13 Squadron which operated Lockheed Hudson light bombers. Six Hudsons, 3 from No. 2 Squadron and 3 from No. 13 Squadron, also arrived at Darwin on 19 February after having been evacuated from Timor. None of the six Wirraways at Darwin on the day of the raid were serviceable. At the time of the event, there was no functional radar to provide early warning of air raids, and the town's civil defences were dysfunctional. The Lowe Commission, which was appointed to investigate the raids shortly after they occurred, was informed that the Australian military estimated that Darwin would have needed 36 heavy anti-aircraft guns and 250 fighter aircraft to defend it against a raid of the scale which occurred on 19 February. In addition to the Australian forces, ten United States Army Air Forces (USAAF) Curtiss P-40 Warhawks were passing through Darwin en route to Java on the day of the attack. The P-40 pilots were largely inexperienced in combat. A total of 65 Allied warships and merchant vessels were in Darwin harbour at the time of the raids. The warships included the United States Navy (USN) destroyer and seaplane tender . The RAN ships in port were the sloops and , corvettes and , auxiliary minesweepers and , patrol boat Coongoola, depot ship , examination vessel , lugger , and four boom-net ships. Several USN and Australian troopships were in the harbour along with a number of merchant vessels of varying sizes. Most of the ships in the harbour were anchored near each other, making them an easy target for air attack. Moreover, no plans had been prepared for how the ships should respond to an air raid. In addition to the vessels in port, the American Army supply ships and Florence D., former Philippine vessels acquired as part of the South West Pacific Area command's permanent Army fleet earlier in February, were near Bathurst Island bound for the Philippines with arms and supplies on the morning of the raid. Darwin was attacked by aircraft flying from aircraft carriers and land bases in the NEI. The main force involved in the raid was the 1st Carrier Air Fleet which was commanded by Vice-Admiral Chūichi Nagumo. This force comprised the aircraft carriers , , , and and a powerful force