The lack of transport aircraft was another constraint. On 5 August, the only two aircraft available for supply work returned to Australia. On 17 August, a Japanese air raid on Port Moresby destroyed five aircraft and severely damaged eleven others when the aircraft had been parked close together. Of these, seven transports (later dubbed "biscuit bombers") were destroyed or put out of commission, leaving only one in service. This report by Gillison is indicative since there is considerable variation in the sources as to the number and type of planes damaged and destroyed. What is clear is that this was a disastrous event that significantly curtailed the Allied capacity to resupply the troops fighting along the track. Moremon says that no aircraft were available for dropping until 23 August while McCathy states this as 22 August. Given the tenuous supply situation, this was a significant break. Civilian aircraft and pilots were pressed into service in an effort to meet demand. They were mainly used in flights between Australia and New Guinea or in rear areas in order to release military planes and personnel for service in forward areas but this did not solve the immediate problem.