This is one of those things where I have a slight disagreement with what is apparently mainstream thought on this website. Everyone here says oh war is immoral and only a government would make war, but there are times that isn’t the case. Let me point out two of them.

One: an free, anarchist community of significant size has finally been established (call it Ancapistan), and a neighboring government wants them to submit to rule. They say no. The government says yes, and marches armed troops into Ancapistan to enforce obedience. Needless to say before long shots are being fired (what a hypocrite I am – apparently I don’t think it’s needless to say because I just said it). Both sides are fighting, and there are a very large number of people on each side – does this situation not count as a war? Yes, I realize the government started it in this scenario, but the anarchists could have just submitted and there’d have been no war. So in a sense it was both sides that made war.

Two: This time, instead of a government invading Ancapistan, the Ancapistanis (someone call me out if that’s not the correct noun form) decide to liberate the people enslaved by a government. The people of the country in question are a great deal more oppressed than we are today and as a result most of them realize that the government is the problem and that it needs to go. They would start a revolution themselves but the state already took their weapons a long time ago so they can’t really do that. Ancapistan to the rescue: the Ancapistanis attack the agents of the state in a heroic effort to bring freedom to the people. This time it’s clearly the Anarchists that made war.

I realize you could argue that even in the second scenario the government started the aggression (by archating against the people the Ancapistanis tried to liberate) but consider this: war ain’t war unless both sides are fighting. If the victims aren’t fighting back, you don’t have war, you just have a massacre. Therefore the anarchists started the war, and it was the right thing to do.