It wasn't until 1991 that the world learned of Marine Corps veteran Charles Benjamin "Chuck" Mawhinney's 103 confirmed kills during his time deployed to Vietnam in the late 1960s.
That count made him not only the deadliest sniper of the Vietnam War, but also the deadliest sniper ever to serve in the Marine Corps. But Mawhinney never mentioned his exploits or record to friends or family; it only came out because a fellow sniper wrote a book giving him the title.
Like so many such claims do, Mahwinney's purported record caused a bit of an uproar in the Vietnam veteran and sniper communities. But it turned out that not only was the book accurate, it might have underreported his accomplishments. It was an even more incredible feat, given his young life and that he almost never joined the Marine Corps in the first place.