The sea was a site for trade, transport and warfare between countries and kingdoms, and its control was thus significant in the shifting dynamics of the region. Merchants and mercenaries formed guilds to better serve their purposes, aligning themselves upon occasion with various allies for mutual benefits.
At the height of its power, the Hanseatic League controlled trade in the North and Baltic seas, and comprised a network of more than 200 towns extending from the United Kingdom to Russia.
