The Japanese threat was further underlined on 19 February, when Japan bombed Darwin, the first of many air raids on northern Australia. Churchill attempted to divert I Corps to reinforce British troops in Burma, without Australian approval. Curtin insisted that it return to Australia. Roosevelt supported Churchill, offering to send an American division to Australia instead, while the Chief of the General Staff Lieutenant General Vernon Sturdee, threaten to resign if his advice was ignored and the troops were diverted to Burma. Curtin prevailed, although he agreed that the main body of the 6th Division could garrison Ceylon.