In March 1968, members of the 23rd Infantry Division slaughtered about 500 Vietnamese civilians in the hamlet of My Lai. Reporter Seymour Hersh exposed the massacre the following year.
By then, Gen. William C. Westmoreland, commander of U.S. forces in Vietnam at the time of My Lai, had become Army chief of staff. A task force was assembled from members of his staff to monitor war crimes allegations and serve as an early-warning system.
Over the next few years, members of the Vietnam War Crimes Working Group reviewed Army investigations and wrote reports and summaries for military brass and the White House.
The records were declassified in 1994, after 20 years as required by law, and moved to the National Archives in College Park, Md., where they went largely unnoticed.
The Times examined most of the files and obtained copies of about 3,000 pages -- about a third of the total -- before government officials removed them from the public shelves, saying they contained personal information that was exempt from the Freedom of Information Act.
In addition to the 320 substantiated incidents, the records contain material related to more than 500 alleged atrocities that Army investigators could not prove or that they discounted.
Johns says many war crimes did not make it into the archive. Some were prosecuted without being identified as war crimes, as required by military regulations. Others were never reported.
In a letter to Westmoreland in 1970, an anonymous sergeant described widespread, unreported killings of civilians by members of the 9th Infantry Division in the Mekong Delta -- and blamed pressure from superiors to generate high body counts.
"A batalion [sic] would kill maybe 15 to 20 [civilians] a day. With 4 batalions in the brigade that would be maybe 40 to 50 a day or 1200 to 1500 a month, easy," the unnamed sergeant wrote. "If I am only 10% right, and believe me it's lots more, then I am trying to tell you about 120-150 murders, or a My Lay [sic] each month for over a year."
A high-level Army review of the letter cited its "forcefulness," "sincerity" and "inescapable logic," and urged then-Secretary of the Army Stanley R. Resor to make sure the push for verifiable body counts did not "encourage the human tendency to inflate the count by violating established rules of engagement."
Investigators tried to find the letter writer and "prevent his complaints from reaching" then-Rep. Ronald V. Dellums (D-Oakland), according to an August 1971 memo to Westmoreland.
The records do not say whether the writer was located, and there is no evidence in the files that his complaint was investigated further.
James D. "Jamie" Henry was 19 in March 1967, when the Army shaved his hippie locks and packed him off to boot camp.
He had been living with his mother in Sonoma County, working as a hospital aide and moonlighting as a flower child in Haight-Ashbury, when he received a letter from his draft board. As thousands of hippies poured into San Francisco for the upcoming "Summer of Love," Henry headed for Ft. Polk, La.
Soon he was on his way to Vietnam, part of a 100,000-man influx that brought U.S. troop strength to 485,000 by the end of 1967. They entered a conflict growing ever bloodier for Americans -- 9,378 U.S. troops would die in combat in 1967, 87% more than the year before.
Henry was a medic with B Company of the 1st Battalion, 35th Infantry, 4th Infantry Division. He described his experiences in a sworn statement to Army investigators several years later and in recent interviews with The Times.
In the fall of 1967, he was on his first patrol, marching along the edge of a rice paddy in Quang Nam province, when the soldiers encountered a teenage girl.
"The guy in the lead immediately stops her and puts his hand down her pants," Henry said. "I just thought, 'My God, what's going on?' "
A day or two later, he saw soldiers senselessly stabbing a pig.
"I talked to them about it, and they told me if I wanted to live very long, I should shut my mouth," he told Army investigators.
Henry may have kept his mouth shut, but he kept his eyes and ears open.
On Oct. 8, 1967, after a firefight near Chu Lai, members of his company spotted a 12-year-old boy out in a rainstorm. He was unarmed and clad only in shorts.
"Somebody caught him up on a hill, and they brought him down and the lieutenant asked who wanted to kill him," Henry told investigators.
Two volunteers stepped forward. One kicked the boy in the stomach. The other took him behind a rock and shot him, according to Henry's statement. They tossed his body in a river and reported him as an enemy combatant killed in action.
Three days later, B Company detained and beat an elderly man suspected of supporting the enemy. He had trouble keeping pace as the soldiers marched him up a steep hill.
"When I turned around, two men had him, one guy had his arms, one guy had his legs and they threw him off the hill onto a bunch of rocks," Henry's statement said.