Schleswig-Holstein, state in northern Germany, 6,046 sq mi (15,660 sq km) bordering Denmark. The capital, Kiel, lies at the eastern end of the Kiel Canal, which links the North and Baltic seas. The main economic activities are dairy farming, fishing, shipbuilding, and engineering. Schleswig was a Danish fiefdom from the 12th century. Holstein came under Danish control in the 15th century. Disputes with the German states led to the Austro-Prussian War in 1864. Prussia annexed these 2 Danish duchies in 1866. North Schleswig was reunited with Denmark in 1920.