In 1941, Earl enlisted in the U.S. Army’s new experimental ski and mountaineering unit. The unit was later known as the 1st Battalion, 87th Mountain Infantry, part of the 10th Mountain Division. He retired from service as Lieutenant Colonel in 1946. He moved to Colorado and joined the National Ski Patrol at Arapahoe Basin. He was instrumental in creating the National Association of the 10th Mountain Division and served as its first National President.