1968: The year that shook the world by the world's greatest photographe rs

IN THE 1960s young people in the West felt boundlessly optimistic. And 1968 was the year when exhilaration reached its apogee. Student leaders found that they could call on tens of thousands of their peers to join demonstrations. They did not need "adult" backing. They could create their own political power. So when President Lyndon Johnson made the astonishing announcement in March that he was not going to run for a second term in the White House, he told a friend: "I felt that I was being chased on all sides by a giant stampede ... I was being forced over the edge by rioting blacks, demonstrating students, marching welfare mothers, squawking professors and hysterical reporters."

Likewise President de Gaulle was terrified when faced in May with a month of riots that were begun by students in Paris and taken up by the might of the French trade-union movement. To reassure himself about the strength of the state, he secretly visited his generals. Afterwards he told Georges Pompidou, his prime minister: "For the first time in my life, my nerve failed me. I am not very proud of myself."

Yet 1968 was also a year when heroes were slaughtered. The exemplary leader of American blacks, Martin Luther King, was shot dead in Memphis in April. He preached non-violent protest - "There is masculinity and strength in non-violence." A few weeks later, in Los Angeles, Senator Robert Kennedy, President Kennedy's younger brother, was also assassinated. Bobby Kennedy spoke directly to young people. In a speech in South Africa he had said: "There is discrimination in this world, and slavery, and slaughter and starvation ... the answer is to rely upon youth - not a time of life but a state of mind, a temper of the will, a quality of the imagination, a predominance of courage over timidity."

Then on 20 August came the news from Czechoslovakia that Soviet troops had crossed the border to snuff out Alexander Dubcek's 200-day experiment in giving socialism a human face. In that short period, censorship had been abolished and the failures of 20 years of communist rule had been identified and discussed. When the invasion began, thousands of Czech and Slovak students were abroad on holiday because travel documents had never before been so easy to obtain.

How did the self-confidence of young people arise? The post-war baby bulge had come of age. In mid-decade there were a million more unmarried 15- to 24-year-olds in Britain than 10 years before. The universities had expanded to accommodate the better-educated among them. The rest were in work. Unemployment was low. Everybody had money. Yet many young people, especially students, felt that somehow life was too easy. They had not suffered like their parents, who had gone through the War and, before that, through the Depression of the 1930s. They wanted to find their own ideals.

They were influenced by Marx, by Freud (and one of his disciples, Marcuse), and particularly by the French philosopher, Jean- Paul Sartre. Sartre had argued that "man is forlorn, because neither within him nor without does he find anything to cling to. Man is condemned to be free; because, once thrown into the world, he is responsible for everything he does." How like this existentialist philosophy are the sentiments of Bob Dylan's "Like a Rolling Stone", released in 1965. Dylan sang: "How does it feel? / How does it feel? / To be on your own / with no direction home / Like a complete unknown / Like a rolling stone."

Young people also had new freedoms. The contraceptive pill had arrived in 1960 and its use soon spread rapidly. Drug-taking suddenly caught on. When David Horowitz, the American writer, returned to California in 1968, he found that "people even looked different. Peace symbols and crystal pendants had replaced crucifixes and Stars of David as emblems of religious conviction. Clothes were tie-dyed and bucolic, colours psychedelic, and hair long ... women were going bra-less ... a band, booming through amplified speakers ... produced an effect something like entering a new dimension ... I felt: a new world is possible."

Young people, too, had discovered a powerful means of self-expression - rock'n'roll, which became the popular culture of the world. A contemporary critic remarked that "the closest Western civilisation came to unity since the Congress of Vienna in 1815 was the week when Sgt Pepper's album was released - in every city in Europe and America, the stereo system and radio played."

For students, the campus itself became the battlefield. In Britain, the newly opened Essex University saw the most violence. Similarly, the Paris student demonstrations began at the new university of Nanterre in the city's suburbs before moving to the Sorbonne. However, in the United States the most serious student riots took place at the venerable Columbia University in New York.

Everywhere student movements had the same, vague ideal in mind - a more participatory democracy. Robert Kennedy praised his democratic opponent, Eugene McCarthy, for making "citizen participation a new and powerful force in our political life". Young radicals dreamed of a socialism without tyrants, of workers' councils, of small firms grouped together in a collective economy, of grass-roots decision-making.

In this light the Vietnam war was the perfect cause celebre. Had not the USA got into Vietnam without consulting its people? Was not the war kept going by the defence establishment, which was indifferent to public opinion? Did not the success of the North Vietnamese Tet offensive, when the walls of the US embassy in Saigon were breached, show the hopelessness of American policy? And did not the remarks attributed to an American officer that it was sometimes "necessary to destroy a town in order to save it" demonstrate the utter futility of the whole enterprise?

Indeed the most violent demonstration in Britain during 1968 took place on 17 March in Grosvenor Square in front of the US embassy. Thousands gathered to protest against the war in Vietnam. Vanessa Redgrave handed in a petition. Some 200 were arrested. Perhaps by French or American standards it was a feeble affair. But then our contribution to the spirit of '68 was powerful in different ways, above all through the music of the Beatles and the Rolling Stones, and through style and street fashions - we invented the mini-skirt.

Towards the end of the 1960s, gay rights and feminist ideals were added to the list of demands. In the United States the authorities' reaction became more violent. Later in 1968, the democratic convention in Chicago turned into a pitched battle as student leaders claimed that America had become a police state. In 1970, at Kent State University, four students were killed. In 1973, the first oil crisis hit the prosperous West. The mood darkened. It would never be "glad confident morning again".