By September 1941 , the USAAF was reinforcing its air bases in the Philippines with B - 17 heavy bombers .
The Australian War Cabinet agreed secretly to an American request for space at the Townsville and Darwin air bases to develop their own ferrying facilities .
By September 1941 , the USAAF was reinforcing its air bases in the Philippines with B - 17 heavy bombers , and the Australian War Cabinet agreed secretly to an American request for space at the Townsville and Darwin air bases to develop their own ferrying facilities .