Leaving Mostar, in Bosnia and Herzegovina, I drive south to yet another nation that emerged newly independent from the ashes of Yugoslavia: Montenegro. During my travels through this region, my punch-drunk passport has been stamped, stamped, and stamped again. While the unification of Europe has made most border crossings feel archaic, here the breakup of Yugoslavia has kept them in vogue. Every time the country splintered, another border was drawn. The poorer the country, it seems, the more ornate the border formalities. By European standards, Montenegro is about as poor as it gets. They don’t even have their own currency. With just 600,000 people, they decided, “Heck, let’s just use euros.” For me, Montenegro, whose name means “Black Mountain,” has always evoked the fratricidal chaos of a bygone age. I think of a time when fathers in the Balkans taught their sons that “your neighbor’s neighbor is your friend” in …