WASHINGTON -- Seventy-five years ago, U.S. forces began the invasion of Luzon, the largest and most populous island in the Philippines, thereby fulfilling Army Gen. Douglas MacArthur's 1942 pledge to recapture the island from the Japanese.Since the Japanese controlled nearly every island between the Philippines and Hawaii in 1942, getting to the Philippines meant seizing many of those islands, which included Guadalcanal, Saipan, Tinian, Tarawa and Peleliu. The islands would provide runways for U.S. aircraft and deny them to Japan.Rather than strike directly at Luzon, Army and Navy planners decided first to capture the Philippine islands of Leyte and Mindoro to the south. Two airfields were established on Mindoro in late December 1944 from which aircraft would be launched to assist in the upcoming landings on Luzon.A U.S. fleet of some 70 ships carried 175,000 troops from the 6th Army to the beaches of Lingayen Gulf, on northwest Luzon, where the landings took place, Jan. 9, 1945. A naval bombardment of the shore assisted.Then on Jan. 15, a second smaller invasion took place, 45 miles southwest of the capital Manila.Ultimately, 10 U.S. divisions and five independent regiments would see action on Luzon, making it the largest campaign of the Pacific war and involving more troops than the United States had used in North Africa, Italy or southern France.After heavy fighting, elements of the 1st Cavalry Division entered Manila, Feb. 4, 1945. In so doing, the soldiers liberated a camp holding about 4,000 civilian prisoners.Liberating Manila, the largest city in Southeast Asia, was not easy, however. Fighting continued until March 4, 1945, when the city was officially declared liberated.Capture of Manila didn't end the fighting, which continued in the hinterlands of Luzon right up until the surrender of Japan, Aug. 15, 1945.Casualties on both sides were staggering. Around 230,000 Japanese were killed on Luzon.American casualties were also high. Ground combat casualties for the 6th and 8th Army were 10,380 killed and 36,550 wounded.By the summer of 1945, the Americans had thus destroyed nine of Japan's best divisions and made another six combat ineffective on Luzon. Losses stemming from the battle so drastically reduced Japanese air power that their use of kamikaze operations was necessary throughout the rest of the war.It should be noted that Mexican and Australian troops also participated in the battle for Luzon, as well as a very large number of Filipino fighters.Incidentally, before and during the war, the Philippines was a commonwealth of the United States, similar to the status of Guam and Puerto Rico today. In 1946, the U.S. recognized the Philippines as an independent nation.