This is a very perceptive point Kevin Drum makes:
It is, often, not so much war itself that people long for, but the moral certainty that comes with it; thus the venom directed even toward those who are skeptical of war, let alone those who are resolutely opposed to it. It's not that the skeptics prevent the hawks from getting the war they want — they usually don't — but that they deny them the moral certainty they so desperately yearn for. And that cannot be tolerated.That explains a lot. Go read the whole post.