From a Washington Post story by Nick Hilden headlined “4 acclaimed novelists talk about writing Vietnam”:

Tim O’Brien

Tim O’Brien was drafted into the Army and sent to Vietnam in 1969. He served in the country’s central Quang Ngai province, a circumstance that at one point brought him through the site of the infamous My Lai Massacre — in which more than 500 Vietnamese civilians were murdered by American troops — about a year after it occurred but before news of it was revealed.