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.

The more interesting question is whether you can make higher levels of government depend more explicitly on lower levels, instead of the other way around