>>82513
>A military inherently demands order and structure which is not voluntary
A certain order, yes. There is no saying that it must be organized exactly the way it is now. Certain troops and armies have more leeway than others. You can't have peasants running all around the battlefield, but you really don't have to go all the way like the Prussians did, not always.
That said, whatever order you need, you can achieve voluntarily. Just have a volunteer army. Anarchocapitalism means no one is bound by any oath he didn't take or contract he didn't sign, but if he does take an oath and does sign a contract, that's a different thing.
>fighting a war is mostly about pre-emptively killing someone before they have the chance to kill you.
You don't have to wait for someone to actually shoot you before you can defend yourself. If he makes sophisticated plans to kill you and steal your land and wife, then you can do whatever it takes to defuse the situation, including killing him, if that is necessary. His bad if he questions your right to live. The positive law, the one we live under, doesn't allow pre-emptive self-defense, because that is challenging the monopoly of force of the state and its ability to defend you. Self-defense is supposed to be the ultima ratio.
>Not to mention that if an invasion is prevented, all the enemy has to do is lay down his arms and NAP would prevent the soldiers of anarchy from finishing them off. Ergo the state can always pull back, rebuild, attack again.
Not necessarily. If you think they will come back from their surrender, you can take them prisoner to prevent them from fighting again. And if they caused damages and killed people, you can punish them for that.
>My question is: How can, say, a continent under anarchy hope to defend itself against a continent under state control?
Same way a state would. The initial mobilization and coordination might be harder, as the military would likely be more decentralized, and it would have fewer relative resources to command, as war socialism and conscription would not be an option. However, with a free territory under its control, it could command more absolute resources. Compare South Korea with North Korea. The North is far more militarized, and yet the South is more advanced, has much better equipment, and would likely defeat it in a conventional fight. That's because the South has the stronger economy, and doesn't have to mobilize as many resources in relative terms to have more in absolute terms.
Whether the state or the anarchist territory would win would depend on a lot of historical accidents and contingencies. The anarchist territory might be defeated quickly if the offensive side of the war is the stronger one, as it was in World War II, when Hitler steamrolled everyone with his Blitzkrieg. (Which, by the way, was a way of compensating for his shitty equipment; France had twice the number of tanks as Germany.) If it's a war that can be won with high-tech equipment (as the US pretends every modern war is), then Ancapistan will surely prevail. All we can say is, we'd have a fighting chance, and a pretty good one. That we'd win, we cannot say. War follows few constant laws.