Northern Europe was the site of another great medieval experiment in statecraft, the Hanseatic League of cities that monopolized trade in the Baltic and North Seas. In a time and place of weak central authority, German-speaking cities in the northern tier of the Holy Roman Empire were the most powerful force in Northern Europe. They waged war against territorial states, winning steep concessions from the Danish Empire in 1370 that marked the league’s zenith. What was the source of Hanse power? Lübeck in northern Germany was the de facto capital. This city was the product of German migratory conquests in a vast Christianization effort. Soon it was an alpha city in a far-flung network that controlled trade from England to Russia and points between. The league led by Lübeck was locked in a zealous, centuries-long struggle to gain and protect trading privileges in the burgeoning financial centers of a new urban age. The Hanse cities formed a network within a network, establishing strongholds in the globally significant nodes of Bergen, Bruges, London, and Novgorod.