Carlos Hathcock, who had dreamed of being a U.S. Marine his whole life, became the Vietnam War's deadliest sniper in missions that sound like they were pulled from the pages of Marvel comics.

Gunnery Sgt. Carlos Hathcock was the kind of Marine that would inspire generations of warfighters. He engaged in sniper duels and came out on top every time. He hunted Viet Cong and North ...