Margaret MacMillan is Provost of Trinity College in the University of Toronto, and Warden-elect of St Anthony's College, Oxford. Her Peacemakers, which covered the Paris Conference of 1919, won numerous awards including the BBC4 Samuel Johnson Prize, and was a bestseller on both sides of the Atlantic.

In 1972 Nixon amazed the world by going to China. The first trip ever by a US President marked the end of deep freeze in Sino-American relations that started with the Communist takeover in 1949. It was an immense gamble but a brilliant stroke of policy, which changed the international balance of power for ever. With China onside Nixon might get out of Vietnam; US knowhow could help Mao recover from his disastrous Cultural Revolution; most of all, each would have backup against the increasingly aggressive Soviet Union. In the longer term, though, was Nixon the supplicant to China, and has the US been at a disadvantage ever since? Will the twenty-first century see co-operation or China challenging American dominance?

This is a fascinating history enacted by extraordinary players: Nixon himself, red-baiter, shrewd statesman, and disgraced politician; Mao, frail, erratic, ruthless; the twin Machiavellis Kissinger and Chou En-lai; brittle, unhappy Pat Nixon; and Mao's wife Jiang Qing, the small-time Shanghai actress become scourge of Chinese cultural arts. And the countries themselves: Communist China, contemptuous but fearful of the outside world, the USA, rich and powerful, and both seeing themselves as models for humanity. The gap between them was huge and still exists today.