The U.S. Sixth Army made a massive amphibious assault on Luzon along the shores of the Lingayen Gulf on 9 January 1945. The Japanese commander, GEN Tomoyuki Yamashita, did not intend to defend the Central Plains-Manila Bay area, but sought only to pin down major elements of GEN MacArthur's forces in order to delay Allied progress to Japan. Nevertheless, strong Japanese forces, primarily naval, disregarded Yamashita's plan and held out in Manila.

     A powerful American force drove down the central valley from the Gulf of Manila, which fell in March after a month of bitter fighting. Yamashita concentrated his forces in three mountainous strongholds where they could conduct a protracted defense. Except for one strong pocket in the mountains of north-central Luzon, where the Japanese were still fighting when the war ended, organized Japanese resistance in Luzon was overcome by the end of May. Meanwhile, the U.S. Eighth Army had completed the operation on Leyte, subdued the Japanese in the southern Philippines in a series of amphibious attacks, and conducted the mop-up phase of operations on Luzon.