Terry de la Mesa Allen, Jr. (1929–1967), son of Terry de la Mesa Allen, Sr., was a fourth generation soldier. He achieved the rank of Lieutenant Colonel. He served with the 1st Infantry Division, which his father had commanded in World War II. He was killed in an ambush in South Vietnam on 17 October 1967, while leading a battalion against the Viet Cong near Lai Khe, northwest of Saigon at the Battle of Ong Thanh. An account of that battle is detailed in They Marched into Sunlight, a book by David Maraniss. Allen was married to Jean Ponder of El Paso and had 3 children; Mary, Consuelo, and Alice.