For generations, and especially since 1945, a colossus has dominated the world through its influence – hard and soft power, cultural and financial, benevolent and malign – as the United States of America emerged from the isolation of its pioneering period to bestride the world stage.

Though often crude and alienating in its approach, sustained by the mighty dollar, even in the days when the nuclear-armed Soviet Union attempted to challenge American hegemony, that dominance, at least in security terms, was ultimately reassuring. America’s political culture became as familiar to the people of most nations as their own: the reverence for the flag, the pledge recited hand-on-heart, the enormous respect paid to the incumbent of the office of President – a title retained for life – and Commander-in-Chief.