Rendsburg (rĕntsˈbŏrkh) [key], city (1994 pop. 31,376), Schleswig-Holstein, N central Germany, a port on the Eider River and the Kiel Canal. The city's manufactures include textiles, fertilizer, and machinery, and there is extensive shipbuilding and ironworking as well as a large agricultural market. Rendsburg passed to the counts of Holstein in 1252 and was chartered soon thereafter. When Schleswig-Holstein rose (1848–51) against Denmark, Rendsburg was made the provisional capital. The Danes, however, regained control of the city and razed (1852–56) its fortress. In 1866, Rendsburg was annexed by Prussia. It has a 13th-century church and a 16th-century city hall.