The Japanese initially landed on batan island in the batanes group,appair, and Vigan in northern Luzon, and Legaspi in southern Luzon, all in the opening days of the war. Davao, in Mindanao, was invaded on 20 December. macArthur’s original defense plan was to hold the enemy at the beaches, but since he lacked enough troops to cover all the beaches, he concentrated the Filipino divisions on the strategic beaches of Lingayen Gulf, Zambales, Batangas, and Quezon province. The main Japanese landing came on 22 December, in Lingayen Gulf. The Japanese landed where the Filipino lines were spread thin. With superior naval , air and land forces, they overwhelmed the Filipino enders, forcing them to retreat. Other Japanese forces landed in Atimonan and Mauban, in Quezon province. Some Philippine Army units fought gallantly, but others were routed and defeated. Seeing the failure of this beach defense plan, MacArthur-on Christmas Eve, 1941-ordered the execution of War Plan Orange and declared Manila an open city. War plan Orange was the standard United stated Army defense plan for the Philippines.