>>89742
>>89788
So that's the economic side. The other is logistics and mobilization.
An ancap society will be decentralized. This will be a huge advantage in some regards, a moderate disadvantage in others. When you have ten PMC's defending the country, then mobilizing and coordinating them for big offensives might be hard, although you can assume they won't be complete retards about it (or no more complete retards than the generals in countries with a government).
The advantage is that with a decentralized military, including a decentralized command structure, the military as a whole will be harder to disrupt. Hiter did just that with the Blitzkrieg. People think, often implicitly, that it was about his superior military capacities, that he just steamrolled over his enemies by virtue of sheer power and speed, but that wasn't always true. He had 2800 tanks against France's 5800, so if France had intercepted the Nazis at once, they would've been destroyed. However, France was too slow to mobilize, and by the time it could react, its military command was decapitated and communication severely hampered. Ancapistan might have done the interception properly, but if it hadn't, then it wouldn't have been hit so severely. A Blitzkrieg against Ancapistan would not end so well, because with so many communications hubs and centers of command, you couldn't disrupt all of them with one strike.
How well Ancapistan would fare would also be a matter of historical contingency. There is no way around that. Sometimes, war is more offensive in nature, and sometimes more defensive. Potentially, Ancapistan might be better at adjusting these contingencies, because more traditional but less successful generals would lose out to innovators, instead of being kept for prestige reasons or because dismissing them would cause an uproar even though their strategies and tactics haven't changed in 1920.
The best book on warfare I know of is J.F.C. Fullers The Conduct of War. If you find it, read it!