Was World War II a mistake?

A bestselling book by Nicholson Baker entitled Human Smoke argues that fighting World War II was a mistake.

But, but, what about the Holocaust? The Jews died anyway, says Baker. More lives were lost fighting the war than were worth the cost. Baker maintains that the pacifists of that time were right.

Where does one start with this? I fear, though, that the anti-war spirit is becoming so strong that this mindset will prevail in the West, and that it is already in Europe.