Rendsburg

Rendsburg stands on the Eider in the borderland between Schleswig and Holstein, where river crossings and roads connect northern and southern districts. Markets, crafts, surrounding agriculture, and transport supported the town. Its position gave fortification and administrative institutions an importance beyond ordinary local exchange. Waterways and routes across the peninsula linked communities with both North Sea and Baltic commercial worlds, although the practical conditions differed greatly along each passage.

Rendsburg's position on an island in the Eider made it a contested border town. Under Danish rule it became a major fortress and garrison: a substantial defensive complex was built in 1669–1673 and expanded again from 1690. The Eider Canal, completed in 1784, connected the town to Kiel and created a waterway between the Baltic and North Sea via the Eider.