In reply to:

In short, we have a word for a martyr, an assassin, a murderer, and so forth. But what do we call that system that produces these en masse or leads them to battle? And what are these people themselves guilty of? Patriotism?

One such system was called National Socialism. At Nuremburg, it was decided that those people were guilty of murder and other "crimes against humanity" and they were punished accordingly. There are trials now going on at The Hague, and someone was sentenced just this week, for the same thing.

There are two difficulties with this, however. The first is that it is seldom possible to bring such culprits to book. Pol Pot and his unspeakable cohorts were and have never been held accountable or punished for their incredible crimes against the Cambodians, and there are plenty of other examples of totally inhuman behavior unpunished, as in the Sudan, Afghanistan, etc. The other difficulty is that it is often a question of who wins a war. If Hitler had won the war, or even been able to negotiate some kind of armistice, there would, of course, have been no Nuremburg trials and he would have gotten away with what is arguably the worst conduct in the history of the world.

There is no escaping the inevitable observation that much depends on whose ox is gored. The Civil War / War Between the States, was fought by one side motivated (at least in part) by a zeal to right the terrible wrong of slavery; while the other side saw themselves as defending their right to secede from the Union if the rest of the states refused to cease meddling in affairs which the various states had an exclusive right to decide without interference from the federal government. When all reasonable efforts to settle this controversy politically had been exhausted, a resort to arms was inevitable. And when the war was over, there were those who wanted to treat Lee and Davis in the same way the US treated the surviving Nazis; but, fortunately for us, cooler and wiser heads prevailed.