Realizing that his plan to defend the Philippines at the beaches is failing, MacArthur sends word to all field commanders that WPO-3, the old War Plan Orange is in effect. Manila is declared an open city and MacArthur's headquarters is moved to Corregidor. OOPS!
Of course two weeks into the war, he has no supplies on Bataan, which will have severe consequences since soldiers can't fight without food, medicine, and ammunition...