The United States assisted its allies materially and supported them operationally. It mobilized US economic and technological resources to arm both the US Armed Forces and those of its allies. The Japanese attack on Pearl Harbor on 7 December 1941 was a transformational event. Far more significant than the damage that the Japanese inflicted upon the US Navy and Army that Sunday morning was the galvanizing effect the surprise attack had on the American body politic. The United States implemented that overall strategy consistently but flexibly, allowing it to respond to opportunities on the battlefield as well as the demands of allies and the American public. Roosevelt compromised where he needed to in order to maintain coalition unity. He husbanded US forces in both the Pacific and the Atlantic until American industrial and technological power could be brought to bear, and then projected American power in both theatres in time to claim victory and shape the post-war order.