After growing up in Vermont, Ernest Harmon attended Norwich University, transferring to West Point after one year, and graduating from there in 1917. He was commissioned in the cavalry after graduation. In World War II he initially served as Commanding General of the 1st Armored Division in Tunisia and Italy. Harmon briefly returned to the United States as a corps commander but then returned to North Africa to command the 2nd Armored Division in 1942-43. After the war he led the VIth Corps, and then for a few months early in 1947 he was the Commanding General of the 3rd US Army. From March 1947 to his retirement in March 1948 he was Deputy Commanding General of all Army Ground Forces. General Harmon left the Army in 1948 and in 1950 was named President of Norwich University, a post he held until 1965.