For a long time, war was simply the continuation of politics. It was just another, normal means of making your point. The greatest knight-army had 22casualties or something(could be 122
and had hundreds of knights fighting eachother. (I don't remember the actual number, but it were a lot of knights considering the few that actually got killed).
Then in 1302 when France decided to collect taxes that were way too high from the Flemisch farmers, the farmers got together and played dirty. We broke some mayor honor rules and slaughtered them all. All of a sudden, Europe had lost 1/3 of the nobles(since they're all used to fighting, which didn't involve a lot of killing up until now).
Fast forwardwind up until WOI, it had been quiet for too long. Peace was getting boring and industry and mass stuff(destruction, transport and such) needed to be shown off. So, we decided to get together and shoot each other some more. Conflict should be settled in a matter of weeks. BUT WAIT! What's this? It's really a MASS conflict where both parties are equally strong. And what's this? We have weapons now what enables us to kill MORE people in shorter periods of time. This is great, let's send as much would-be-civilians to the battleground without proper training. Oe, and look at this, not only do we have gatling guns to butcher them up and instantly kill them, we have (mustard) gass. That way, it takes a while before they die and the army has to take care of them. Swell...
I'll skip the rest of the history lesson, except to say one more thing:
Not just bush a war criminal(no offence to the americans out there, I know you didn't elect him), but at the standards of the nuremberg trails(Chompsky is with me on this) all presidents of the USA are guilty of war crimes.