Along with his partner "Sarge" Clay, Gunner Mackay fought bravely in the Pacific, often helped by Pooch, a dog from the K-9 Corps who saved their lives countless times. Later Gunner and Sarge were assigned to the European front to train a band of raw recruits. Unfortunately, their trainees were slaughtered on their first patrol. The two Marines blamed themselves for this and fell in with fellow misfits Captain Storm and Johnny Cloud to form the outfit known as the Losers. This team went on secret missions until 1945 when Gunner and Sarge were killed by Nazi troops. Gunner survived to see America's Bicentennial. He met for a reunion along with his fellow "Losers", Captain Storm, Sarge and Johnny Cloud. Gravedigger, Jeb Stuart and Mademoiselle Marie also attended. How his body was revived through Project M and his survival into 1976 are conflicting. It is unknown how old his revived body was when Project M found him. Gunner's body was revived by the top secret Project M. Fitted with cybernetic implants that made his body a walking weapon, Gunner Mackay became a member of the Creature Commando's, battling intergallactic invaders, but he still misses his old friend Sarge.