It is a delicious irony, but also a significant one, that “Churchill, Hitler, and the Unnecessary War” (Crown, 518 pages, $29.95), Patrick J. Buchanan’s new contribution to the flourishing genre of World War II revisionism, should appear in the same season as Nicholson Baker’s “Human Smoke.” Never has there been such a clear demonstration of the way ideological extremes tend to converge.

Messrs. Baker and Buchanan probably could not stand to be in the same room for five minutes. The former is to the left of most Democrats, the latter to the right of most Republicans. When they look back to the 1930s, Mr. Baker’s role models are the Quakers and pacifists who believed it was better to lie down for Hitler than take up arms to fight him; Mr. Buchanan’s are the isolationists who believed that Nazi Germany was a necessary bulwark against the real menace, godless communism. But the net result of their lucubrations is the same. Both men have written books arguing that World War II, far from being “the good war” of myth, was an unnecessary folly that Britain and America should never have engaged in. And both have zeroed in on Winston Churchill as the war’s true villain — an immoral, hypocritical, bloodthirsty braggart whose fame is a hoax on posterity.

But where Mr. Baker’s book can be, and in most quarters has been, dismissed as the ignorant blundering of a novelist who wandered far out of his depth, Mr. Buchanan’s book is more dangerous. For Mr. Buchanan, a former speechwriter in the Nixon and Reagan White Houses, was once a notable presence in mainstream American politics. Since the collapse of his second protest candidacy for the Republican nomination for president, in 1996, however, he has in fact left the mainstream behind, not just by associating himself with the fringe Reform Party, but by publishing a series of books whose Spenglerian rhetoric about the decline of the West lays bare the racist and reactionary premises of his thought.

Just from the titles of Mr. Buchanan’s books — “Day of Reckoning,” “State of Emergency,” “The Death of the West” — it is clear that he deploys a rhetoric of violence and treason more redolent of the German right in the Weimar period than of anything in the American conservative tradition. Open the books themselves, and things only get worse. Mr. Buchanan is a man who can write, in “Day of Reckoning,” that “we are on a path to national suicide,” not because he is oblivious to the echoes of the old eugenicist term “race suicide,” but because he positively embraces them.

The “American majority,” he writes — or what he later, more openly calls “white folks” — is “not reproducing itself,” with the result that “Asian, African, and Latin American children come to inherit the estate the lost generation of American children never got to see.” That Asian, African, and Latin-American children, once they come to America, are American children is a fact that Mr. Buchanan is strangely reluctant to acknowledge — as reluctant as a 19th-century Know-Nothing would have been to acknowledge that an Irish-Catholic like Mr. Buchanan could ever be truly American. How it must gall him to think that the next president of America might be named Barack Hussein Obama.

What happens when such a man turns to World War II, which in so many ways created and defined the America he loathes — an America whose 19th-century isolationism gave way, under the pressure of necessity and the lure of opportunity, to liberal internationalism? “Churchill, Hitler, and the Unnecessary War” provides the answer, though as his title suggests, Mr. Buchanan’s critique of contemporary America is made only indirectly. Ostensibly, the targets of his invective are Churchill and the British Empire, and his argument strictly a historical one. Not until his closing pages does Mr. Buchanan state explicitly what has been evident all along, that his blast at the British past is really a polemic about the American future. “There is hardly a blunder of the British Empire we have not emulated,” he writes, and he concludes with the putatively sinister image of President Bush contemplating a bust of Churchill.

Mr. Buchanan’s historical argument itself is pedestrian, a series of clichés enlivened only by malign sophistries. Most of the book is dedicated to retelling the most often told story of the 20th century, the suicide of Europe in the two world wars. Here once again are the guns of August, on loan from Barbara Tuchman, and the rise and fall of the Third Reich, as told by William Shirer. When Mr. Buchanan is not quoting venerable, popularizing histories like these, he is quoting the most popular of their revisionists — such as Niall Ferguson, who argued in “The Pity of War” that Britain should not have entered World War I. By far the most important source for Mr. Buchanan, however, is the British military historian Correlli Barnett, whose book “The Collapse of British Power” is quoted very copiously. (Mr. Barnett may have endeared himself to Mr. Buchanan with his vocal opposition to the Iraq war; in another nice example of extremes converging, Noam Chomsky has cited Mr. Barnett in his own anti-war writings.)

Mr. Buchanan’s total reliance on the work of historians — there is no sign in this book that has opened a scholarly journal or delved into an archive — makes it a bit rich for him to claim that he is out to overturn some historians’ consensus or conspiracy. “Historians today,” he writes, “see in Hitler’s actions [during the 1930s] a series of preconceived and brilliant moves on the chessboard of Europe, reflecting the grand strategy of an evil genius unfolding step by step … This is mythology.” The only mythology here is the existence of such naive “historians,” none of whom Mr. Buchanan actually names. In fact, almost all of Mr. Buchanan’s contentions have long pedigrees. When he writes that the Treaty of “Versailles had created not only an unjust but unsustainable peace,” he is echoing what John Maynard Keynes wrote in the very year of the treaty, and what is now as close to a commonplace as history can show.

There is really only one controversial claim in “Hitler, Churchill, and the Unnecessary War.” This is the notion that Britain should not have offered to guarantee Poland against Nazi aggression in April 1939, and so would not have had to go to war when the aggression came that September. This would have been the wiser course, Mr. Buchanan argues, because Hitler had no interest in war with Britain. In fact, he admired the English as racial comrades, and more than once floated the prospect of the two nations dividing up the world between them. His real target was the Soviet Union, and it would have been better for Britain and the world to allow those two monstrous tyrannies to fight each other alone.

It is hard to say which aspect of this argument is more objectionable, the factual or the ethical. Factually — or, rather, counterfactually — it is ludicrous to suggest that Britain would have been better off allowing Germany a free hand in Eastern Europe. When Hitler did invade the Soviet Union, in June 1941, he came within a hairsbreadth of immediate victory, pushing deep into Russian territory and enslaving or killing millions upon millions of civilians. Had Britain not been in the war at that point, had Hitler been fighting Stalin alone, there is good reason to think that the Wehrmacht would have been in Moscow by the end of the year. At that point, of course, it would have been truly suicidal for Britain to declare war on Germany, and Hitler would have been free to concentrate on invading the British Isles or starving them into submission. Only by getting into the war when it did, even at a very unpropitious moment, did Britain have a chance of ultimate survival.

Mr. Buchanan’s arguments against this overwhelming conclusion are notably feeble. Hitler might have turned west after defeating Stalin, he writes, “But why?” Here Mr. Buchanan’s weak grasp of strategy merges with his weak grasp of ideology. For he writes about Nazi Germany as a “realist,” that is, as one who believes that its ideological character was less important than its power-political goals. Hitler wanted to reunite the Germans severed from the fatherland by Versailles, Mr. Buchanan argues, so there is no reason to think that he would have gone on to conquer the whole continent of Europe. Mr. Buchanan could have been cured of this delusion by reading Hannah Arendt’s analysis in “The Origins of Totalitarianism,” in which she lays bare the distinctive quality of Nazism (and Stalinism): that it was not a party but a movement, which could keep itself alive only by constant motion, new conquests, new transformations of society.

Hitler himself made very plain that Germany was only the beginning of his ambitions, which ran to the complete reorganization of the world as a racial hierarchy. Left to his own devices, Hitler would have completed the genocide of the Jews, made Poland and Ukraine German slave colonies, depopulated Russia, and committed even more horrors against the “Christian peoples” for whom Mr. Buchanan professes such solicitude when contemplating their sufferings under communism.

Churchill, of course, was the one British statesman who recognized that a Europe dominated by Hitler could never be at peace, and who never wavered from the consequences of this insight. Here lies his greatness — here, and not in every act and pronouncement of his long, checkered career, which Mr. Buchanan maliciously combs through. Perhaps those who only know Churchill as a name or a bulldog profile will be surprised by Mr. Buchanan’s disclosures — that Churchill was impetuous, a bad military strategist, an unregenerate imperialist. It is rather nauseating, however, to see Mr. Buchanan, of all people, impugning Churchill for racism. He devotes a section of his book to Churchill’s anti-immigration stand in the 1950s: Churchill believed that “Keep England White” was “a good slogan,” while Mr. Buchanan calls it “an astonishing slogan in a day when Dr. Martin Luther King … was starting out in Montgomery.” He is even brazen enough to write that, had Churchill prevailed, England would not have become “the multiracial, multicultural nation of today.”

When one remembers that if there is one cause Mr. Buchanan himself cherishes it is immigration restriction — when one recalls his words on “national suicide” and the “invasion” of America by nonwhites, and his constant inveighing against multiculturalism — when one remembers that the first pages of this very book lament that “as a share of world population, peoples of European ancestry have been shrinking for three generations,” that “we are slowly disappearing from the earth” — Mr. Buchanan’s feline criticism of Churchill stands as a piece of truly shameless hypocrisy.

In any case, everything that was weak in Churchill’s character and objectionable in his politics was well-known during his lifetime. In the mid-1930s, indeed, he was one of the most unpopular politicians in Britain. The reason why he came back from exile to be named prime minister in May 1940, England’s darkest hour, was not because he was a perfect statesman but because he was indomitable: “We shall go on to the end, we shall fight in France, 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.” Pity the nation that reaches a point where it needs a Churchill to save it; but pity even more a nation that, needing a Churchill, fails to find one.

akirsch@nysun.com