It was while covering the Vietnam War for the Associated Press that he took his best-known photograph – the picture of police chief General Nguyen Ngoc Loan executing a Vietcong prisoner, Nguyen Van Lem, on a Saigon street, on February 1, 1968, during the opening stages of the Tet Offensive.

Adams won the 1969 Pulitzer Prize for Spot News Photography and a World Press Photo award for the photograph (captioned ‘General Nguyen Ngoc Loan executing a Viet Cong prisoner in Saigon’), but would later lament its notoriety.

Adams wrote in Time:

The general killed the Viet Cong; I killed the general with my camera. Still photographs are the most powerful weapon in the world. People believe them; but photographs do lie, even without manipulation. They are only half-truths.

What the photograph didn’t say was, ‘What would you do if you were the general at that time and place on that hot day, and you caught the so-called bad guy after he blew away one, two or three American people?’

Adams later apologized in person to General Nguyen and his family for the irreparable damage it did to Loan’s honor while he was alive. When Nguyen died, Adams praised him as a “hero” of a “just cause”.

He once said that “I would have rather been known more for the series of photographs I shot of 48 Vietnamese refugees who managed to sail to Thailand in a 30-foot boat, only to be towed back to the open seas by Thai marines.” The photographs, and accompanying reports, helped persuade then President Jimmy Carter to grant the nearly 200,000 Vietnamese boat people asylum. He won the robert Capa Gold Medal from the Overseas Press Club in 1977 for these series of photographs in his photo essay, “The Boat of No Smiles”. Adams remarked, “It did some good and nobody got hurt.”