I think in places like Northern Ireland one can most readily see the damage done by the concepts of statism and nationalism, as well as by the specific governments or government-like groups. On can also clearly see the the advantage of the alternative: more than one "governing" company, not linked to a particular territory, akin to today's cell phone companies.
Having watched bits and pieces of a documentary on the conflict in Northern Ireland, I have little doubt that had the organizations representing the British, as well as the Catholic and the Protestant Irish been free-market anarchist "protection agencies", voted for by the people with their money and interested in maximizing their profit, they would very quickly come to a peaceful resolution of the conflict — since the alternative is so bloody expensive and wasteful.
This is the answer to the question: "Won't the protection agencies go to war with each other under anarchy?" Well, first of all, it can't be too much worse than what we've had, throughout human history, with the governments involved (the governments have been the single greatest source of death, injury and general misery in the history). Only the organizations whose basis is political support could drag out the ridiculous bickering conflict over three decades with thousands of people dead on all sides. Second, why would they? If their goal is not some idiotic nationalist agenda, but maximizing the profit, they would realize that carrying out a wasteful war is not wise from economic point of view and would quickly reach a solution.
A comment from an article about Ireland:
I’d long dreamed that the “six slave counties” of Northern Ireland would become independent and the first truly libertarian “state.” (In [quotation marks] because a state without taxes wouldn’t be a state as states are known to be.) The North’s mostly-Protestant “Unionists,” so called, favor union with Great Britain as a buttress against being ruled by Catholic Irishmen, which would happen if the North became part of the Irish Republic. Loyalty to Britain extends no farther than staving off Catholic rule, for Unionists have been ready to take up arms against British forces whenever the North was threatened with being dumped by the Brits into the Republic.More on the subject (despite the problems with punctuation, it is a very interesting article).
Mostly-Catholic “Republicans,” on the other hand, favor becoming part of the Irish Republic to the south primarily as a means of escaping rule by historically tyrannical Britain or its surrogate unionist government. Republicans haven’t forgotten the fact that their Irish brethren to the south, with whom they joined in battle against British rule in the years leading up to the establishment of an Irish Free State, negotiated a treaty establishing a semi-Irish independence that left them behind and under surrogate-British (Unionist) rule, which proved to be even more oppressive of Irish Catholics than the Brits had been.
With the population of the northern slave counties divided roughly equally between adamant Unionists and adamant Republicans, each unequivocally opposed to being ruled by the other, what better place could there be for establishing a country where nobody rules anybody? Unfortunately, at least for the time being, the so-called “leaders” of Unionists and Republicans have chosen “power-sharing” as a solution to the Irish “Troubles,” rather than renouncing the power to rule over others as the only sure means to lasting peace.
The situation described above actually reminded me of the one in Somalia. There, the warlords go to war with each other only when the "peace-keeping" UN troops get involved, with their repeated attempts of establishing a "democratic government". Each warlord starts feeling threatened that the other warlords will gain political power, backed up by the West, and thinks that he has to make his move first. When the UN troops are not involved, the warlords live in an equilibrium with each other, with traditional tribal laws being the legal framework for the society.