[MathMonkeyMan]

I haven't studied history or political science, but I suspect that a bunch of cooperating individual local municipalities can as easily lead to war as to federalism.

The Federalist Papers talk a lot about factionalism versus tyranny. On a larger scale, look at how long it took what are now European Union members to stop warring with each other.

[jleyank]

Greek city states and German petty kingdoms suggest conflict and failure to unite vs external threats common.