Russia’s recent buzzing of NATO ships and planes in the Baltic points to something bigger. In the past several years Russia has engaged in a major naval and military buildup in the Baltic region. The epicenter is the city of Kaliningrad, Russia’s forward operating base, located on the south shore of the Baltic between Lithuania and Poland—about 600 miles southwest of St. Petersburg, Russia. The Kaliningrad area houses the Russian Baltic fleet and two air bases. It boasts Russia’s only year-round ice-free port on the Baltic Sea.

On April 14, a Russian jet barrel-rolled over a U.S. reconnaissance plane doing a routine flight in international airspace over the Baltic Sea. That followed an incident on April 12 in the Baltic Sea, when Russian jets made close-range and low-altitude passes near a U.S. navy destroyer engaged in joint exercises with its NATO ally Poland. 

Hannibal of Carthage (in modern Tunisia) was one of history’s greatest generals. He invaded Italy in the third century BC and nearly brought Rome to its knees. At Cannae in southern Italy in 216 BC Hannibal won one of the most crushing victories in all of military history—and it is only the most famous of his battlefield successes.

In the sixth century BC, King Cyrus the Great founded the Persian Empire, the largest realm in human history to date. His advisors suggested that Cyrus relocate his people from their rugged homeland in southwestern Iran to a more imperial seat in one of the lush lands that they now controlled. Cyrus said no; he called the plan a recipe for ruin...