John, Duke of Marlborough, was captain-general of the European coalition, which frustrated Louis XIV’s plan to create a French superstate and dominate the Continent, and was decisive in turning Britain from a marginal power into a great one. He has always aroused passion and controversy – among the politicians and the public during his lifetime, and among historians since. He was given a ferocious drubbing by Macaulay, who sometimes relied on biased and dodgy sources. Macaulay in turn was savaged by Winston Churchill, whose huge biography of his forebear put the Duke back on his pedestal. Then along came Trevelyan, with his three-volume England under Queen Anne. He thought ‘Macaulay was wrong in his reading of Marlborough’, but added that Churchill has no right to call Macaulay ‘a liar’. Trevelyan, it seems to me, got the balance about right, and his book, which I have been rereading while preparing this review, is a masterpiece.