1^st Infantry Regiment

The 1st Infantry Regiment entered the war as one of the 6th Infantry Division's prewar Regular Army regiments, training at Camp Jackson, Fort Benning, Fort Francis E. Warren, Fort Leavenworth, Fort Leonard Wood, Camp Young, and Camp San Luis Obispo before sailing through Hawaii to New Guinea. It reached Milne Bay in February 1944 and moved to the Toem area in June. During the Lone Tree Hill battle, the regiment came in by sea west of the hill to outflank the Japanese position and forced a beachhead that was difficult to expand while the 20th Infantry attacked from the Tirfoam River.

The regiment's first major amphibious assault came at Sansapor on July 30, 1944. Landing without preliminary bombardment to preserve surprise, its battalions moved rapidly through light or nonexistent opposition. The 2nd Battalion pushed inland and east from Red Beach, the 1st Battalion searched the dense jungle westward, and the 3rd Battalion moved along the coast to the Wewe River before making an unopposed landing at Cape Sansapor the next morning. It secured Sansapor Plantation and village, then patrolled west toward the Mega River while disease, especially scrub typhus and fever, became a major enemy.

On Luzon the 1st Infantry landed at Lingayen Gulf on January 9, 1945, then drove toward Urdaneta as the division opened the Cabaruan Hills line. On February 4, with air support, it seized San Jose, the gateway to Highway 5 and the Cagayan Valley. A short Bataan operation followed, during which the regiment helped cut the peninsula from Abucay to Bagac. Recommitted northeast of Manila, it fought in the Shimbu Line, attacking toward Mount Mataba, Benchmark Hill, Mount Baytangan, and Wawa Dam. In April it pushed onto Woodpecker Ridge near the Bosoboso-Marikina junction before being relieved. It spent the war's final months in northern Luzon security and occupation preparations, then moved to Korea after Japan's surrender.