Vermont was born in Mount Victory, Kentucky, on 29 October 1915. He attended Eastern Kentucky State University. On March 17, 1941, Garrison enlisted in the United States Army and became an aviation cadet in Class 41-C at Muskogee, Oklahoma, but washed out of advanced flight training at Brooks Field, Texas, in October. Garrison promptly enlisted in the Royal Air Force at Dallas, Texas and completed flight training at El Centro, California. After obtaining his RAF wings, Pilot Officer Garrison was shipped to England, where after further training he was promoted to Flying Officer and made a gunnery instructor, posted to RAF Hawarden to train pilots flying North American Mustangs. He transferred in July 1943 to the newly formed USAAF, 4th Fighter Group. There he was assigned to the 336th Squadron, where he flew P-47 Thunderbolts and P-51 Mustangs.

His first victory was on 16 December 1943, and by February he had achieved four more victories and had become an "Ace". A month later he was shot down by ground fire and spent the rest of the war as a POW.

He had 7 1/2 victories in WW II, and had earned the Distinguished Service Cross, the Silver Star with an Oak Leaf Cluster, the Legion of Merit with an Oak Leaf Cluster, the Distinguished Flying Cross with six Oak Leaf Clusters, the Bronze Star with two Oak Leaf Clusters, the Purple Heart, and the Air Medal with many Oak Leaf Clusters.

During the Korean War he commanded the 3596 Training Squadron at Nellis AFB, Nevada for two years. Back in combat in Korea, he was 4th group Commander of 335th Fighter Squadron. He shot down his first MiG in February 1953 and became a Korean War "Ace" in June.He then became a "double-Ace" one month later with his 10th victory.

Promoted to Colonel in 1961, he returned to combat for the third time as Vice Commander of the 8th Tactical Fighter Wing. There he flew F-4C Phantoms out of a base in Ubon, Thailand. He retired in 1973, one of only seven to achieve "Ace" status in two wars.

In February 1994 he suffered a fatal heart attack at Mt. Home, Idaho.