Nicholas Warr grew up in Oregon and attended Brigham Young University and the University of Oregon before enlisting, at the age of twenty, in the United States Marine Corps. Warr was recommended for the Enlisted Commissioning Program by his Drill Instructors in Boot Camp, and subsequently attended OCS at Marine Corps Base, Quantico, Virginia. Warr graduated from OCS and was commissioned in March 1967.
After attending The Basic School and a six-week high-intensity Vietnamese language training course, his first assignment as an infantry officer sent him to Vietnam from November 1967 until December 1968. He served with the 1st Battalion, 5th Marines, 1st Marine Division as a Platoon Commander, Company Executive Officer and Company Commander during some of the toughest fighting in the Vietnam War.
Warr's unit was awarded the Presidential Unit Citation for participation in Operation "HUE CITY" during the Tet Offensive of 1968, and he was honorably discharged as a first lieutenant in March 1970.