There had been angry demands for a US withdrawal, not least in America itself. Since the casualties mounted – over 50,000 Americans were to become killed – a tide of anti-war protest swept the country. The US president, Lyndon B Johnson, was so concerned at the political damage the war was causing that in March 1968 he ordered a partial halt towards the bombing of North Vietnam in order to get peace talks started.

These began in Paris in May, and also the bombing of the North stopped completely in October. But the talks made little or no progress and the war, far from ending, really intensified as US forces attacked Vietcong bases in Laos and Cambodia. In 1972, the Americans also resumed the bombing of North Vietnam. Eventually, in January 1973, a ceasefire agreement was signed by the United States, North and South Vietnam, and also the Vietcong.

By April, all 500,000 US troops in South Vietnam had been withdrawn. The South survived until 1975, when the North Vietnamese Army (NVA) launched a full-scale invasion. Without American help, the South Vietnamese army melted away and Saigon fell towards the NVA on 30 April. It was renamed Ho Chi Minh City, and North and South Vietnam had been formally reunited since the Socialist Republic of Vietnam in 1976.

But fresh trouble was already brewing across the border in Cambodia (now renamed Kampuchea), where power had been seized by a Communist guerrilla group known as the Khmer Rouge. Led by the tyrannical Pol Pot, they launched a reign of terror, killing all those who disagreed with their actions, or who belonged to groups they disliked. Anybody wearing spectacles, for example, was liable to become executed as an ‘intellectual’. During the four years of Khmer Rouge rule, at least a million Cambodians – some 20% of the population – perished. The terror ended in 1979, when the NVA entered Cambodia and forced Pol Pot and his followers to flee.

Even though the invasion prevented even much more Cambodians from being massacred, it was condemned by both China and America. China, a one-time friend, attacked Vietnam’s Northern provinces, while America, the former enemy, led an international trade boycott against it. In 1989, the NVA pulled out of Cambodia. After much more than four decades of war, Vietnam was finally at peace.