Churchill was indeed a defender of empire and held some serious racial prejudices, especially against Indians, whom he detested. But he was also an internationalist. Far from wanting Britain to go it alone during the evacuation of Allied troops from Dunkirk in the spring of 1940, he even entertained the idea that Britain and France should merge as one nation to fight Hitler.

The idea of Britain’s special relationship with the United States was also very much Churchill’s. His mother was American, so there were sentimental reasons. And Churchill was a great believer in the greatness of the “English-speaking peoples.” But the relationship was born out of dire necessity. Churchill knew that Britain would not be able to defeat Nazi Germany without active help from the United States.

Roosevelt, who was no friend of British imperialism, was well aware of the danger posed to the United States by a Europe dominated by the Third Reich. But in 1940, most Americans were not at all keen to go to war to help Britain. The most fervent opposition came from right-wing isolationists, and some of them, such as the aviator Charles Lindbergh, had more than a sneaking sympathy for the Nazis. Their slogan, revived by the Trump campaign in 2016, was “America First.”

At the end of 1941, the Japanese attack on Pearl Harbor and Hitler’s declaration of war against the United States silenced the America Firsters. Churchill and Roosevelt drew up the Atlantic Charter, envisioning the world after Hitler’s defeat. It was marked by deeply internationalist ideas: cooperation between countries, free trade and political freedom for all. The United Nations, now much disdained by the Trump administration, was born from this charter.

After the war was won, Churchill gave a famous speech in Zurich, in which he called for the creation of a United States of Europe. He believed that only full European integration would stave off another devastating war. Quite where Britain fit into this grand European design was left a little vague. Churchill thought that Britain, the United States and the Soviet Union should at least be sympathetic patrons of a united Europe. Many members of his generation had a hard time seeing Britain as just another European country, on a par with France or Italy. Among the 52 percent of Britons who voted for Brexit, there are plenty who find this difficult still.