The plan worked. Immigrants soon began arriving in force, and Lübeck became the leading entrepôt for the budding Baltic Sea trade route, which eventually extended as far west as London and Bruges and as far east as Novgorod, in Russia. Hundreds of oaken cogs—ships powered by a single square sail—entered Lübeck’s harbor every year, their hulls bursting with Flemish cloth, Russian fur, and German salt. In less than a century, Lübeck went from a backwater to the most populous and prosperous town in northern Europe. “In medieval urban history there is hardly another example of a success so sudden and so brilliant,” writes the historian Philippe Dollinger.