I just finished Patrick J. Buchanan's Churchill, Hitler and the Unnecessary War, his argument that Great Britain and the United States should not have fought Germany in either 1914 or 1939. It's part of Buchanan's polemic against the neocons, and a big part of it is his attack on their idol, Winston Churchill. In it, he seems to say that what the neocons do today, exaggerate foreign threats by equating them with Hitler, Churchill did with Hitler himself, exaggerating the dictator into a would-be world conqueror.
Buchanan echoes an old strain of Germanophilia in American culture that hasn't really had strong expression since the days of H.L. Mencken. He feels that Germany has gotten a bum rap for World War I and didn't deserve the treatment it got in the Versailles Treaty. He blames Britain for prodding Europe toward war before 1914 because it was unwilling to accept Germany's rightful(?) status as the inevitable Great Power of Europe, and faults Churchill in particular for an unexplained lifelong bias against Germany. He thinks Europe should have accommodated Hitler as long as he presented legitimate German grievances, and that Britain was supremely unrealistic in trying to guarantee Polish security in 1939, since they succeeded only in guaranteeing a world war.
The old-school Germanophilia Buchanan hints at usually came with a degree of Anglophobia readily seen in Mencken's writings. This viewpoint portrays Britain as the arrogant busybody of nations, presuming to tell other countries how to conduct themselves while their own actions proved them hypocrites. Buchanan doesn't really share this viewpoint. He isn't Anglophobic, and appears deeply to regret what he considers one of the main consequences of the World Wars: the loss of the British Empire. Nevertheless, there's a messianic element among some Brits, including Churchill, which he sees as a precursor to neocon foreign policy, including an impulse to unite British and American forces into an unstoppable force for good. Buchanan recognizes Britain and America as nations with inevitably differing national interests which should act accordingly, albeit amicably. Instead, Buchanan actually suggests that Churchill sold Britain out to the U.S. in the vain thought that Americans would share his vision of joint dominion.
Buchanan's nostalgia for European imperialism is disturbing. He seems to sneer at Woodrow Wilson's notion of self-determination for all nationalities, noting that the victors of World War I proved themselves hypocrites by denying self-determination to millions of Germans whose territory was given to other countries. But while he's all for German self-determination, he regards the subjugation of Czechoslovakia, Poland, etc. with complacency. To a degree he even blames these nations for their fates, citing instances when they allegedly went out of their way to provoke Hitler.
The main argument for World War II being unnecessary for Britain is the fact that, by 1939, that country could do nothing to save Poland. Buchanan is unmoved by any argument that the principle of the thing should count for something. It was simply foolish to guarantee the security of a country when you couldn't do it. He allows that a stronger stand might have stopped Hitler in Czechoslovakia (which had a modern army, unlike Poland), but he defends the signers of the infamous "Munich" agreement, arguing only that they should have used the time they bought to re-arm, not necessarily to fight, but the better to intimidate Hitler when he tried more mischief.
The war was even less unnecessary, both for Britain and America, as far as Buchanan is concerned, because Hitler wasn't a threat to them. He offers a piecemeal refutation of all the supposed evidence that Hitler wanted to conquer the world, but while some of his own evidence (like Hitler's refusal to build a large-scale navy) is persuasive, too often he relies on second-hand interpretations of Hitler's intentions. Buchanan's book is based mostly on second-hand sources, and is open to criticism on the ground that he might have selected works that already agreed with his own opinion instead of letting the evidence determine his verdict.
Toward the end Buchanan's latent bias against Communism becomes overpowering. Another reason he deems World War II unnecessary and unfortunate is that it allowed Stalin to conquer Eastern Europe. While he shrugs off Hitler's conquests with little more than formal protests against Nazi brutality, Buchanan clearly gets much more worked up over Stalin's tyranny. He thinks that if Britain laid off Hitler, the German would have followed the fall of Poland immediately with a war on Russia that would have bled both regimes white. Strangely, he doesn't speculate on how that war would have turned out, leaving us only his assumption that Poland and the rest of Eastern Europe would have been better off if the war hadn't played out as it actually did. Likewise the fall of the British Empire and its European relations opened doors to Communists all over the world, which to this supposedly cold-eyed realist is an unbearably bad thing.
Buchanan closes with a comment on the current American situation, suggesting that the Bush administration had succumbed to Churchillism, which might be summarized as the belief that it is imperative to wage war on bad rulers because tyrants are incapable of restraint. He contrasts this approach to America's Cold War policy, which was to build up military power as a deterrent against the USSR, but not to attack it or its Warsaw Pact satellites. Eisenhower, Nixon, and Reagan knew when to pick their battles and when to keep their distance, while the Bushes couldn't stop themselves from going after the "evil" ones. Just as Britain overextended itself out of obsessive fear of an "evil" Germany, and as Churchill was willing to commit any atrocity to destroy the "evil" Hitler, so the younger Bush has tried to bankrupt America's treasury and its honor to crush "evil" terrorists and "Islamofascists."
I don't know if whether anyone "had to" fight Hitler is a question historians can answer. On some level it's a moral question, unless you mean it in terms of national interests. Either way you ask it, Buchanan's answer is no, and I'm not sure if any set of evidence set in front of him would change his mind. It would probably be a good thing if there were a force available to fight any dictator who invaded any other country, as long as that force wasn't itself to any one nation or party of nations, and was prepared to deal equally with any violation of sovereignty. Ideally, the international community ought to be as ready to stop one country from invading another as any person should be to stop a mugging in the street. We shouldn't want to deny this point out of fear that the slippery slope will take us into Iraq with the American army, and we shouldn't let our feelings about Iraq and the neocons lead us to endorse Buchanan's complacent view of Great Power politics. People like Hitler may indeed need to be eliminated, even if by an international assassin's guild out of some people's fantasies. It would be interesting to learn whether Pat Buchanan would endorse a theoretical assassination of Hitler. The answer might make me revise my assessment of a questionably argued but definitely thought-provoking volume.