John Brewton was born on September 5, 1943, in Mobile, Alabama. He graduated from the University of Alabama in Tuscaloosa, Alabama, in 1966, and entered Officer Candidate School with the U.S. Navy on November 25, 1966, receiving his commission as an Ensign in the Navy at Newport, Rhode Island, on April 14, 1967. Ens Brewton next attended Underwater Demolition Team Replacement training with Class 40 (East Coast) at NAB Little Creek, Virginia, where he graduated in August 1967. His first assignment was with SEAL Team TWO at NAB Little Creek from August 1967 until he died of wounds received in combat in South Vietnam on January 11, 1970. While serving with SEAL Team TWO he deployed to South Vietnam from June to December 1968, and again from February 1969 until he was badly wounded in November 1969. LTJG Brewton was posthumously promoted to Lieutenant, and the frigate USS Brewton (FF-1086) was named in his honor. John Brewton was buried at the Mobile Memorial Gardens Cemetery in Tillmans Corner, Alabama.

His Silver Star Citation reads:

For conspicuous gallantry and intrepidity in action on 24 November 1969 while serving with friendly foreign forces engaged in armed conflict against the North Vietnamese and Viet Cong communist aggressor forces in the Republic of Vietnam. As Assistant Platoon Officer of a U.S. Navy SEAL Team, Lieutenant (jg) Brewton was participating in a mission in the Rung Sat Special Zone, in an area of recent heavy enemy activity, when he observed a camouflaged sampan, an enemy bunker, and two armed Viet Cong. As he gave the command for the platoon to open fire, the unit was simultaneously taken under heavy enemy fire from a numerically-superior force. Although wounded in the arms and back, Lieutenant (jg) Brewton led his platoon to offensive firing positions. He was again wounded while firing from a prone position. Despite his additional painful injuries, he directed the corpsman to care for other, more seriously wounded personnel, and remained in a forward exposed position to direct U.S. Navy Light Helicopter Fire Team air strikes on the enemy. Only after the enemy fire was suppressed and the other casualties treated did he accept medical aid for himself. By his valiant leadership and courageous fighting spirit in the face of grave enemy opposition and serious personal injuries, Lieutenant (jg) Brewton upheld the highest traditions of the United States Naval Service.