"Vietnam was a great war for photographers," writes David Halberstam in his introduction to the book Requiem, which is also the title of a forthcoming exhibition of work by "the photographers who died in Vietnam and Indochina". When I met Horst Faas, the double Pulitzer Prize-winner and the co-editor of Requiem (with Tim Page), at the London office of Associated Press, he explained: "Vietnam set an example of photojournalism that has become an eternal marker for all subsequent wars." Every photographer who walks through those offices, whether covering conflicts in the Balkans or Chechnya, is still trying to emulate what was achieved by the photojournalists in Vietnam.
This view was echoed by Eamonn McCabe, the Guardian's former picture editor, who spoke to me about how so many classic images came out of Vietnam - the bandaged hand, the napalm explosion, and so on. "It inspired people to get into photojournalism," he reminisced. "Kids went around wanting to be the new Don McCullin."
Vietnam provided a unique set of opportunities. The loose nature of the conflict and the confusion on the battlefields allowed photojournalists unprecedented free rein. It was an unusual war, in that photographers (except those working for the communist North) did not have to represent a particular side. French, British, Korean, Thai, Hong Kong Chinese, Vietnamese, German, Cambodian, Swiss and Australian photographers simply shot what was happening, regardless of which side it suited. Many American photographers arrived later on, after the story had broken, but their attitude was much the same.
Such liberty would be limited after Vietnam. Photojournalists covering future US conflicts including Grenada, Panama and the Gulf would be subject to restrictions. McCabe was struck by how the photographers in Vietnam simply did their own thing, enabling them to get so close to events: "There were no rules; they could go wherever they wanted and just join in."
Faas knows better than most how different the situation is today, when it's all about moving in and out fast. "I was in Vietnam for ten years, not pulled out after three days." Francois Sully spent 24 years photographing the Indochina and Vietnam conflicts. Back then, news did not function as daily entertainment.
"Now you have to get pictures, regardless of quality, every day," said McCabe ruefully. In Vietnam, it did not matter if it took six weeks for the pictures to return: they would still be printed.
The photographers usually worked alone. There were no press pools, no divisions by country. There was simply no room for groups of three or four on a helicopter. Sometimes they worked in pairs, but would often separate on a patrol, not seeing each other for days. The autonomy brought many dangers. It was crucial, revealed Faas, to assess quickly whether the patrol you were moving with was good or careless: "Some Vietnamese units were really bad, some US ones were even worse. Being with one of them was a risk to your life." He was not afraid to admit to pulling out of an operation because it was "bad news".
The unlimited access was not just opportunistic. The South Vietnamese soldiers were happy to have photographers along because they saw that the world cared about what was happening in their country. Larry Burrows got permission from the South Vietnamese government to be strapped to a wing of an old Second World War plane so he could shoot from outside the cockpit. The US forces were also welcoming. The photographers moved around so much of the country that they were a great source of information to the soldiers as to what was happening elsewhere.
The US soldiers wanted the public to know what was going on; hence the photographers were often able to talk their way into the last seat on the helicopters that were their lifelines for seeing the serious action. When Faas was in Saigon, he would regularly take a car to the airport, hitch a DC3 on its morning mail and casualty run to a military base, and from there take a helicopter into the fighting. At times, it wasn't even that difficult, as Halberstam points out: "You could hire a cab in Saigon for a few dollars and drive to My Tho, go to war if you wanted, and it was there every day, yours for the mere asking."
The photojournalists were the first to bring home the true story of Vietnam. When photographers such as Burrows and Faas arrived in the early days of 1962 - because they had heard of "something brewing" - there were only a few thousand "invisible" US troops. The American public back home was scarcely aware of any conflict. As pictures started filtering back, featuring uniformed Americans in situations of violence and suffering, the nation's conscience was jolted.
The watershed came on 25 January 1963. Life, then the most powerful magazine in the US, published its first cover story on the Vietnam war. The 14-page spread used a selection of astonishing pictures taken by Burrows while accompanying combat missions. The Vietnam conflict had arrived in mainland America. Photos such as the double-page "body count", with US soldiers in the background, proved that the Americans were helping the South Vietnamese fight and kill communists in a real war on the other side of the world.
I asked Robert Fisk, the Middle East correspondent for the Independent, about the difference the photographs had made. He told me, from Beirut: "The pictures added a narrative effect, which ordinary people otherwise would just not have had." In other words, without the photos, Vietnam would have been just another story.
Alex Burmaster is the co-director of MineMedia.net and a freelance writer
Requiem: by the photographers who died in Vietnam and Indochina edited by Horst Faas and Tim Page is published by Jonathan Cape (£40)
"Requiem" is at the Proud Galleries, 5 Buckingham Street, London WC2 (020 7839 4942), until 20 September