Seventy years ago this summer, in June of 1940, an aging British politician, who for the previous twenty years had seemed to his countrymen to be one of those entertaining, eccentric, essentially literary figures littering the margins of political life, got up to make a speech in the House of Commons. The British Expeditionary Forces had just been evacuated from France, fleeing a conquering German Army—evacuated successfully, but, as the speaker said, wars aren’t won that way—and Britain itself seemed sure to be invaded, and soon. Many of the most powerful people in his own party believed it was time to settle for the best deal you could get from the Germans.

At that moment when all seemed lost, something was found, as Winston Churchill pronounced some of the most famous lines of the past century. “We shall go on to the end,” he said defiantly, in tones plummy and, on the surviving recordings, surprisingly thick-tongued. “We shall fight on the seas and oceans, we shall fight with growing confidence and growing strength in the air, we shall defend our Island, whatever the cost may be, we shall fight on the beaches, we shall fight on the landing grounds, we shall fight in the fields and in the streets, we shall fight in the hills; we shall never surrender.” Churchill’s words did all that words can do in the world. They said what had to be done; they announced why it had to be done then; they inspired those who had to do it.

That fatal summer and those fateful words continue to resonate. Revisionism, the itch of historians to say something new about something already known, has nicked Churchill without really drawing blood. In American conservative circles, he is still El Cid with a cigar, hoisted up on his horse to confront the latest existential threat to Western civilization (though his admirers tend to censor out the champagne or cognac glass that this ferocious Francophile kept clamped there, too). In Britain, it’s a little different. Just as J.F.K. is adored abroad and admired at home—where by now he’s seen as half liberal martyr, half libertine satyr—Churchill in Britain is revered but quarantined, his reputation held to the five years of his wartime rule. The Labour grandees Roy Jenkins and Denis Healey treat Churchill in their memoirs as a historical figure deserving of affection and respect but not really part of the story of modern Britain. (Jenkins eventually wrote a life of him, and ended up surprised by his own high opinion.) The revisionism from Churchill’s own side is more marked; some on the British right even see him as the man who helped lose the Empire in a self-intoxicated excess of oratory that was the sort of thing only Americans would take seriously. It is typical of what his American fans can miss that a writer for the Wall Street Journal recently quoted Gore Vidal calling Evelyn Waugh a kind of prose Churchill, and thought this flattering to Waugh. In fact, Waugh disliked Churchill, prose and politics alike—his alter ego, Guy Crouchback, calls him “a professional politician, a master of sham-Augustan prose, a Zionist, an advocate of the popular front in Europe, an associate of the press-lords and of Lloyd George”—and his dry-eyed, limpid, every-pebble-in-its-place language was utterly remote from Churchill’s sonorous, neo-Latinate sentences, and meant to be so.

But book after book about Churchill still comes: in the past few years a life by the omnivorous biographer Paul Johnson, “Churchill” (Viking; $24.95); a complete collection of Churchill’s quotations, “Churchill by Himself ” (Public Affairs; $29.95); and new and more specialized studies of Churchill at war, Churchill at Yalta, and Churchill in the memory of his countrymen. All these supplement the standard biographies, which include Martin Gilbert’s official multivolume history, published in the nineteen-seventies and eighties, Jenkins’s single-volume life, from 2001, and John Keegan’s crisp and authoritative life, from the year after. Meanwhile, the American historian John Lukacs’s decades’ worth of books about Churchill—slicing fine tranches of the crucial months and weeks and even days—remain the most insightful studies of Churchill’s psychology and political practice. Reading all these, one finds a Churchill who is a good deal more compelling than the eternal iron man. Goethe wrote that Hamlet was a man who was asked to do something that seemed impossible for that man to do. Churchill is a kind of Hamlet in reverse, a man who was called on, late in life, to do the one thing he was uniquely able to do, and did it.

Churchill’s life is so complex that he would have justified a biography or two had he died in 1931, when he was hit by a car on a New York street. The American connection was anything but incidental. He had an American mother, a loyal American audience, and, twice in his life, a determination to bring America into a war. (The editor Maxwell Perkins once said that he seemed to be “much more like an American than an Englishman.”) During a period when Britain was to the world what America is now, the No. 1 nation with a widely admired élan, Churchill always kept a friendly, steady eye on the oncoming American chariot.

At the same time, Churchill was never entirely trusted by the upper crust to which he belonged, and certainly never by its organized voice, the Conservative Party. To be born both at the top of the tree and out on a limb is an odd combination, and that double heritage accounts for a lot of what happened to him later. Some of this oddity he owed to his mother, the New York heiress Jennie Jerome. But he owed more to his father, Randolph, who had been a meteor across the sky in British politics in the eighteen-seventies and eighties.

Randolph came from an old family—Churchill could never get enough of his descent from the first Duke of Marlborough, who defeated French and Bavarian troops at the Battle of Blenheim—but he belonged to a new generation of British politicians. After the golden age of the gentleman-gladiator, the eighteen-sixties and seventies of Disraeli and Gladstone, came a time of professional politics played as a blood sport. Randolph Churchill and his close collaborator (and, later, competitor) Joseph Chamberlain, who made his fortune as an industrialist in Birmingham, represented a new brutality: both were ambitious, driven, and ruthless, with an imperial turn of mind that Winston absorbed as second nature. Randolph, as Secretary of State for India in a Tory government, presented Burma as a “New Year’s present” to the Queen. The imperialism of the older Churchill and Chamberlain appealed to tribal honor in military conquest, cutting right across class lines and limitations.

It may seem mysterious that jingoism should appeal so overwhelmingly to the working classes, easily trumping apparently obvious differences in interests between them and the economic imperialists. Why should conquering Burma be of significance to a Cockney? But imperialism is the cosmopolitanism of the people, the lever by which the unempowered come to believe that their acts have world-historical meaning. This understanding was the spine and bone of the younger Winston’s politics. In his mind, British modernization and progress—and throughout the first part of his career he was seen, above all, as a progressive—were always tied up with the cult and religion of Empire. For Churchill, imperialism and progressivism were parts of the same package. You kept the Empire together by making sure that its very different peoples felt cared for by a benevolent overseer at home. (This faith in government as the essential caretaker led him later to support the creation of a national health service, “in order to ensure that everybody in the country, irrespective of means, age, sex, or occupation, shall have equal opportunities to benefit from the best and most up-to-date medical and allied services available.”)

Lord Randolph resigned in 1886, at his moment of maximum influence, apparently thinking that he could get a chunk of Parliament to follow him. He was wrong, and it is a sign of the changing mood that, where Gladstone resigned and returned as regularly as a soprano, Churchill’s resignation was a death sentence to his hopes. In the spring of 1894, he became mentally unstable. The old story that his sudden decline was due to progressive syphilis now seems untrue—he is thought to have had a brain tumor—but the son must surely have suspected that his father died from venereal disease.

Winston recalled only a few intimate conversations with his father, and one of these, though couched as an apology, stayed with him: “Do remember things do not always go right with me. My every action is misjudged and every word distorted. . . . So make some allowances.” Winston’s own life had, up until the summer of 1940, the same shape of overreach and frustrated hopes. Something subtler came to him as a legacy, though. Having his father’s work to finish, he also belonged emotionally with him in the nineteenth century, in a world of giants of the grand gesture, like Disraeli and Gladstone, who had the self-confidence to let the slightly loony inner man shine through the public mask.

After attending Sandhurst, in the eighteen-nineties, Churchill set out to make a reputation as an imperial warrior. He went adventuring, in South Africa and elsewhere, in a very “Ripping Yarns” spirit, and wrote very “Ripping Yarns” journalism about it. “The British army had never fired on white troops since the Crimea, and now that the world was growing so sensible and pacific—and so democratic too—the great days were over,” he wrote of this period in his life. “Luckily, however, there were still savages and barbarous peoples. There were Zulus and Afghans, also the Dervishes of the Soudan. Some of these might, if they were well-disposed, ‘put up a show.’ ”

He entered politics in 1900, on the strength of his imperial adventures and his family name. If no man is a hero to his valet, every man can be best judged by his personal assistant, and Winston’s longest-serving private secretary, from the time he was elected to Parliament, was the remarkable and ever-admiring man of letters Edward Marsh. It was Marsh who recorded Churchill, on a visit to a poor neighborhood in Manchester, saying, with his odd and signature mixture of real empathy and inherited condescension, “Fancy living in one of these streets—never seeing anything beautiful—never eating anything savoury—never saying anything clever! ”

Churchill earned his way forward by means of his vibrant skills as a debater and a phrasemaker. (“If you want to make a true picture in your mind of a battle between great modern ironclad ships,” he said in Parliament, “you must not think of it as if it were two men in armour striking at each other with heavy swords. It is more like a battle between two egg-shells striking each other with hammers.”) As First Lord of the Admiralty at the start of the Great War, he believed that the slugging match on the Western Front showed a lack of imagination, and his pet project became the doomed invasion of the hinterland of the Turkish Empire, summed up in the name Gallipoli. The idea was to make an amphibious assault on the Gallipoli peninsula, on the European side of Turkey, and, though one official rationale was to open a route to Russia, then an ally, Churchill plainly saw it as a coup de théâtre that would take Constantinople, break the logjam of the war, and astonish the world—a brave imperial coup, another Burma at a still bigger moment.

On the night, the ill-prepared British and Allied troops met grimly resistant Turkish troops, got bogged down and bloodied, and had to be withdrawn. It is an article of faith in Australia and New Zealand that their troops were used by Churchill as cannon fodder, just as it is in Canada that the Canadians were taken by the Brits to serve a similar role at Dieppe, nearly three decades later. This seems on the whole unfair—the incompetent mass destruction of helpless infantrymen was a déformation professionelle of the entire British leadership, playing no favorites. Yet it burned into Churchill’s reputation the idea that he was indifferent to the welfare of the ordinary soldier, and that his theatrical instincts were a mortal danger to privates and political parties alike.

Those who considered him an eccentric rider of hobbyhorses were confirmed in their view when, in the early nineteen-thirties, he routinely denounced Gandhi and Indian nationalism, breaking with the Conservative Party over it. “A seditious Middle Temple lawyer now posing as a fakir of a type well known in the East” was among the milder things he said. One of the reasons that well-intentioned people didn’t take seriously what he soon was saying about Hitler was that he had recently been saying the same kind of thing about Gandhi.

Only when Hitler came to power, in 1933, did Churchill’s great moment begin. Magnanimity in victory was a core principle for Churchill, and he had been generous about Hitler in the beginning, recognizing that a defeated people need a defiant leader. But he soon caught on: “In the German view, which Herr Hitler shares, a peaceful Germany and Austria were fallen upon in 1914 by a gang of wicked designing nations, headed by Belgium and Serbia, and would have defended herself successfully if only she had not been stabbed in the back by the Jews. Against such opinions it is vain to argue.”

People sometimes say that Churchill was quick to spot what Hitler was about because he was a student of history. But everyone in England had a historical line on Hitler: he was a second Mussolini, three parts bluster to one part opportunism; he was, at worst, another Napoleon, with continental ambitions but hardly a monster. Churchill saw that he was a fierce nationalist who had found a way of resurrecting and winning the obedience of the great engine of recent European history, the German Army. “You must never underrate the power of the German machine,” he said, “this tremendous association of people who think about nothing but war.” And then Churchill understood in his bones that Hitler was an apocalyptic romantic, who genuinely wanted a war. Churchill had always been perfectly willing to negotiate with bad guys, even with people he thought of as terrorists: one of the high points of his political career was the agreement for Irish independence that, as Colonial Secretary in the Lloyd George government after the war, he arrived at with the I.R.A. leader Michael Collins, a man who, in Churchill’s mind, was simply a murderer. Churchill not only negotiated with Collins but came to admire his character and dash. Churchill’s point, in the thirties, was not that bad guys should never be placated but that Germans possessed by a big idea and a reformed military are extremely dangerous to their neighbors.