Niall Barr, of the Defence Studies Department at King’s College London, has set himself the difficult but fascinating task of ascertaining to what extent General George C Marshall, the head of the US Army throughout the Second World War, was telling the truth when he stated that the British and Americans achieved ‘the most complete unification of military effort ever achieved by two allied nations’. This is the story of, in Barr’s words, ‘how they cooperated, learned from, and also, at times, ignored one another’.

Employing classic understatement, Barr argues that Anglo-American military cooperation started from ‘rather inauspicious beginnings’ with the defeat of the British forces under General Edward Braddock (whose aide-de-camp was George Washington) by the French and Indians in 1755, just before the Seven Years’ War. After that it collapsed into open hostility in the American War of Independence