In historical terms, the relationship between the US and Europe constituted one of the most intimate in modern times. Indeed, if the US began life as a distinctly European project, Europe's very own ‘Thirty Years’ War’ between 1914 and 1945 brought about a major role reversal. This left the Western powers on the continent less masters of their own house and more dependent on an all-powerful, liberal, hegemon situated 3,000 miles away across the Atlantic. There was no inevitability about any of this. But as one of the more perspicacious international relations theorists noted as early as 1920, if one global war had already tilted the balance of power towards the US another – which he thought was inevitable – would almost certainly finish the job completely. Trotsky did not live to see one of his more brilliant (and this time more accurate) forecasts come true. Nor can we be sure that he would have been altogether happy with this prospect, given the role the US went on to play after the Second World War. But as the dust began to settle after 1945, one thing must have been patently clear to all: the continent that in 1900 could claim the title of ‘world hegemon’ was hegemonic no more. To all intents and purposes, ‘the European age was at last over’.

Inevitably, the international system after 1945 was the very entity of that which had existed before, no more so than in terms of America's relationship with Western Europe. In strictly formal terms, the US and its European allies formed part of a voluntary alliance entered into by self-determining, equal, sovereign states. In effect, the relationship was to be shaped by two realities: a massive imbalance in power and strategic dependency by the Europeans on their American protectors from across the ocean. This was not something that brought much joy to the hearts of all Europeans; even less did it please those who for a short time after the Second World War believed it would be possible to build a third European pole between the superpowers. But the brute facts of the matter meant that the Europeans had little choice but to invite the Americans to become their benign imperial protectors.