Adam Kirsch has a long and interesting discussion in the New York Times about the way in which recent historical work on World War II has put a question mark against any too simplistic understanding of it as, simply, a 'good war' - one neatly fitting the image of 'American might deployed for virtuous ends'. Once one is familiarized with the details of the raid on Hamburg that killed 40,000 civilians and with the 'horrors of the British and American air raids on German cities' more generally; once one considers the bombing of Hiroshima and Nagasaki; once one registers a central fact of that war, namely, that the US and Britain were allied with Stalin (like Hitler, also a gangster) and the Soviet Union, responsible for the deaths of four million civilians and POWs - the view of World War II as a good war is put under some pressure.
Kirsch does not in fact succumb to this pressure, concluding that though it is necessary to restore complexity to the past against over-simplified images of it, this does not undo our reasons for being glad and proud about the defeat of Nazism. It certainly doesn't. I would go further, however, and say that the putative problem to which Kirsch's conclusion is offered as a response is a confected one.
At the heart of thinking about war, there is a distinction between having just cause in going to war and using just methods in waging war that answers to the supposed conundrum of the Allies having resorted to measures that breached the laws of warfare. They did; but that they did places not the slightest question mark against the justice of the Allied cause in the war against Hitler. The reason it doesn't is very easy to state from more general principles: it is perfectly possible for one thing to have both good and bad aspects and still be better, massively better, than another thing which is overwhelmingly bad.