When U Thant retired in 1971 after a decade as secretary-general of the United Nations, he was hailed as ‘Planetary Citizen Number One’. In what he described as ‘the loneliest job in the world’, Thant dedicated himself tirelessly to seeking international peace. He encouraged détente during the Cold War and played a key part in averting a third world war over Cuba. He struggled to devise diplomatic solutions to intractable problems throughout the globe, helping to achieve, for example, a ceasefire between India and Pakistan in 1965. As the retreat from empire accelerated, he championed the rights and interests of colonised peoples, attempting to free Katanga from white supremacy, condemning apartheid in South Africa and denouncing French atrocities in Algeria. In short, Thant provided disunited nations with incomparable moral leadership, doing much to fulfil his ambition to act as the ‘conscience of humanity’. Yet his failures overshadowed his successes and today, according to his grandson Thant Myint-U, he is a forgotten man.

This is not quite right. Thant’s importance as the first non-white UN secretary-general (the first two occupants of the office were the Scandinavians Trygve Lie and Dag Hammarskjöld) has long been recognised. Equally important, as President Kennedy acknowledged at the time, was Thant’s mediation in the 1962 Cuban Missile Crisis. The confrontation began with America’s deployment in Turkey of ballistic missiles that could have devastated huge swathes of Russia. In retaliation, Khrushchev stationed Soviet missiles in Fidel Castro’s Cuba. In doing so, he told his defence chief, ‘Moscow would be stuffing a hedgehog down Uncle Sam’s pants.’

Using taped recordings of White House discussions, historians have produced a detailed appraisal of Thant’s role in the crisis. As tensions mounted, many agreed with Thant that peace was far from guaranteed through a balance of terror and the prospect of mutually assured destruction. Pentagon generals rattled their sabres, a