Where Are Europe’s Fault Lines?

Beneath the surface of modern maps, numerous old fault lines still exist. A political earthquake or two might reveal the fractures for all to see.

Correspondent Mark G. and I have long discussed the potential relevancy of old boundaries, alliances and structures in Europe’s future alignments. Examples include the Holy Roman Empire and the Hanseatic League, among others.

In the long view, Europe has cycled between periods of consolidation and fragmentation for two millennia, starting with the...