The arch-conservative Patrick Buchanan has never found an isolationist cause, other than the anti-anti-communist one, that he didn't like. First he penned A Republic, Not an Empire to make the case for American active disengagement from the world's woes but, apparently unheeded, this hasn't sufficed. Accordingly, in his latest tome, Churchill, Hitler and The Unnecessary War: How Britain Lost Its Empire and the West Lost the World, he has targeted the biggest objection to his preferred course of action – the disastrous consequences of appeasing Nazi Germany in the 1930s. His argument is simple and tries to get out from under: appeasement of Hitler wasn't the culprit – the Allied victors of World War One were.

Buchanan asks: "How did Munich lead to World War II?" and answers – it didn't. Instead, he says, the war-causing event was the Allies' violation of the principle of self-determination by creating Czechoslovakia, which, as he put it in a recent column, absorbed "3 million Germans, 3 million Slovaks, 800,000 Hungarians, 150,000 Poles and 500,000 Ruthenians."

What Buchanan doesn't mention is that there was no way to provide viable self-determination for some groups without creating new minorities, as Europe's populations were deeply entangled. Nor does he disclose that the Munich agreement incorporated 800,000 Czechs into the Third Reich, whose right to self-determination Buchanan lacks the audacity to claim was in any way inferior to that of Germans in Czechoslovakia. These are gaping omissions in an argument claiming that the Allies violated the principle of self-determination. Nor does Buchanan argue for any alternative principle the Allies should have followed.

These omissions enable a disingenuous argument. They convey the false impression that self-determination was a sound, rather than problematic, idea and that it was dishonored by the Allies rather than imperfectly implemented by them. This in turn allows Buchanan to insinuate that the problems of inter-war Europe were the creation of the Allies, rather than inherent in the situation.

Thus, Buchanan presents Nazi demands in 1938 and 1939 as being simply instances of Germans justly seeking self-determination. That in turn entails another omission: failing to mention why applying the principle of self-determination to create Czechoslovakia proved so disruptive that a world war was risked in 1938. After all, many peoples have their minorities in other lands. That is no necessary tragedy. The tragedy is to be everywhere a minority. Yet in 1938, the overwhelming majority of Germans enjoyed self-determination, embodied in the largest, most powerful state in the heart of Europe. Yet even this proved insufficient. Why? Buchanan doesn't say.

The answer is this: the Nazi supremacist policy of conquest and enslavement that anyone who cared to know at the time could have discovered meant that either the Allies would have to concede all Hitler demanded, or war would result. But the appeasers didn't want to know it then and Buchanan, who knows it now, simply strikes it from the record – while belittling the most prominent figure who did understand from the beginning, Winston Churchill. Like the appeasers, Buchanan detaches shards of legitimacy from totalitarian claims – much like present day appeasers of Islamist aggression.

Unfortunately for Buchanan, the historical record is not amenable to this sort of engineering. Issues of self-determination led to world war not because, as Buchanan argues, Britain and France took an imprudent interest in standing by Poland's refusal to disgorge itself of German-populated territories, but because the dynamic aggressiveness of Nazi Germany made a stand at some point imperative.

It was painfully clear by 1939 that Germany did not simply want the Paris peace settlement redrawn as if Germany had not lost: it wanted it rewritten as if Germany had won. In that distinction lies the world of difference between legitimate claims that can be arbitrated, and consuming appetites that cannot be, if I may for once use the word, appeased.

Buchanan tactfully says nothing about why Britain found itself in 1938 at Munich with the unenviable dilemma of either conceding Hitler's demands or going to war with Germany when "she had no draft, no Spitfires, no divisions ready to be sent to France." Yet the reason for precisely this dilemma and these near-fatal deficiencies was years of appeasement – precisely the policy Buchanan is at pains to resurrect.

A refusal to arm and maintain necessary forces to keep the peace; a refusal to reverse Hitler's violation of the peace when he remilitarized the Rhineland in 1936 – something that could have been accomplished easily with available forces when Hitler's armies were as yet too weak and small to face determined opposition; a refusal to make common cause with the Soviets to counter Hitler – all these and more found Britain so fatefully unprepared for the crisis when it came. But Buchanan fixates on Munich, divorced of its historical and moral context, his unctuous tone notwithstanding.

Moreover, however woefully unprepared was Britain for war in 1938, it was in arguably better shape for the supreme test than a year later when it did go to war. True, the Royal Air Force won a year's reprieve in which to build up its strength, which proved hugely important, but the failure to stand firm at Munich was also militarily disastrous. It deprived Britain and France of a Czech ally who, rendered defenseless, was dismembered by Hitler six months later, along with its excellent army of 40 divisions. This freed up 30 German divisions for service elsewhere, handed to Hitler the resources of the Czech arms industry, economy and territories, and brought about the collapse of France's eastern alliances.

In short, abdication at Munich led to the ill-considered and unenforceable guarantee to Poland, which Buchanan deplores – he merely fails to explain that his preferred appeasement policy brought Britain to that very pass.

By its unpreparedness, Britain nearly forfeited its existence, not merely its empire, and had to fight for its life in a monumental war that could have been headed off earlier at much lesser cost by a combination of prudence and moral clarity. Those searching for either will not find it in Buchanan's book. People who neither wish to confront aggression nor inquire into the evil that animates it are the first to find spuriously altruistic reasons for so doing – a truism that can stand as an epitaph for Patrick Buchanan.