The Americal Division (23rd Infantry Division) was formed from elements of Task Force Oregon in Chu Lai, Southern First Corps, Republic of South Vietnam on 26 September 1967. The division, although designated as the 23rd Infantry Division, was most often referred to as the Americal Division in keeping with its jungle fighting lineage from World War II.

Among its many units were three independent light infantry brigades: The 11th Light Infantry Brigade “Jungle Warriors” from Schofield Barracks, Hawaii served primarily in the Duc Pho area; the 196th Light Infantry Brigade “Chargers” from Ft. Devens, Massachusetts served primarily in the Tam Ky area; and the 198th Light Infantry Brigade “Brave and Bold” from Ft. Hood, Texas served primarily in the Chu Lai area.

The division became the largest infantry division in the Vietnam War and its heavily contested area of operations in Quang Ngai and Quang Tin Provinces included more territory than any other division in Vietnam. It operated in diverse terrain from the triple-canopied mountainous central highlands to the heavily foliaged Piedmont to the flat and open coastal plains. Its diverse missions against the Viet Cong and North Vietnamese Army included search and destroy, search and clear, rice harvest protection, and accelerated pacification. The division was inactivated on 29 November 1971 at Fort Lewis, Washington.

For its service in Vietnam the Americal Division and its units received numerous awards of the U. S. Army Presidential Unit Citation, U. S. Navy Presidential Unit Citation, Valorous Unit Award, Meritorious Unit Award, and The Republic of Vietnam Cross of Gallantry with Palm.