All photographers record history; very few change it. Among those who have was Philip Jones Griffiths, whose book Vietnam Inc (1971) played a key role in altering the American public’s perception of the war in South East Asia, and determined — perhaps for the first time — that the abiding images of a war should not be of the combatants but of its victims.

Although the claim has been made before, it would be exaggerating to say that it was Jones Griffiths’s work that led to mass opposition to the war. That had been growing steadily since the mid-1960s, and had been substantially increased by the revelation in 1969 of the My Lai massacre in 1968.

Nonetheless, the US media broadly continued to support the American presence in Vietnam, and accordingly had largely refrained from publishing stories or photographs deemed damaging or harrowing. What Jones Griffiths did was to make widely available for the first time the other side of the picture, and to confront the US with the reality of what was being done in its name.

He had arrived in Vietnam in 1966 with the intention already of compiling a book, and quickly decided that the situation there was not as it was being portrayed to the press by their military minders. For him, the war was not an attempt to prevent the spread of communism but another episode in the post-colonial struggle by Asian nations for self-government.

In this view he was influenced by his own roots. An articulate, emotional Welsh republican, Jones Griffiths identified with the rural Vietnamese, seeing in the American imposition on them of an inimical, industrialised culture a reflection of Wales’s subjugation by England.

Cutting loose from the press corps, Jones Griffiths methodically travelled the country for four years. So unwanted were his resultant images of the suffering of the ordinary Vietnamese that in that time he barely sold a photograph to a news organisation. He saved money by living with a local family, and often had to decide whether to buy film or food.

His subject was not war, but the pity of war. He saw himself as producing a historical document, and (though often converted from colour film) printed his pictures in black and white to signal their profundity and to tone down the blood, believing that gore would make viewers look away.

Among photographs of his that were to become defining images of the war was that of a civilian victim of American fire, face wrapped in bandages, arm labelled as if an exhibit; and that of a GI with his feet up on a window ledge, rifle at the ready, a headless doll beneath his chair. Other shots showed innocent casualties of US rocket fire — giving the lie to American claims that the wounds were inflicted by Viet Cong — and Vietnamese girls prostituting themselves to Marines.

Ironically, given his seriousness of purpose, Jones Griffiths was able to publish Vietnam Inc only thanks to the payment he received for a paparazzo shot, having sneaked into Cambodia to photograph Jackie Kennedy on holiday with Lord Harlech, the former Ambassador to Washington, whom the press thought was her beau at the time.

The book came out at a turning point in the war, and his depiction of its hitherto unseen consequences forced many to contemplate a conflict that they had largely ignored, and helped crystallise opposition to it. Later it would be used as a source for influential films such as Apocalypse Now (1979) and Full Metal Jacket (1987). Time called the volume "the best book of photo-reportage of war ever published", while Henri Cartier-Bresson said: "Not since Goya has anyone covered war like Philip Jones Griffiths." The President of South Vietnam, Nguyen Van Thieu, declared that he was top of the list of people barred from the country.

The photographer, however, repeatedly declared that he had no particular animus against the Americans or their Vietnamese allies. He was, he said, not so much seeking to tell the truth about this war, as about all wars.

Philip Griffiths — he later took his mother’s name too — was born, one of three boys, in Rhuddlan, Denbighshire, in 1936. His mother was a district nurse; his father worked for the LMS railway and, when war came, managed the transport of the National Gallery’s treasures to Welsh caves.