SCHLESWIG (Dan. Slesvig), a town of Germany, capital of the Prussian province of Schleswig-Holstein. It is situated at the west end of the long narrow arm of the sea called the Schlei, 30 m. to the N.W. of Kiel on the railway from Hamburg to Vamdrup, on the Danish frontier. Pop. (1905) 19,032. The town consists mainly of a single street, 3½ m. long, forming a semicircle round the Schlei, and is divided into the old town (Altstadt), Holm, Lollfuss, and Friedrichsberg. The church of St Peter, erected about 1100 and renewed in the Gothic style in the 15th century, has a lofty steeple (365 ft.) and contains a very fine carved oak reredos by Hans Brüggemann, which is regarded as the most valuable work of art in Schleswig-Holstein. Between Friedrichsberg and Lollfuss on an island between the Schlei and Burg See is the old château of Gottorp, now used as barracks. The former commercial importance of the town has disappeared, and the Schlei now affords access to small vessels only. Fishing, tanning, flour-milling and brewing are the chief industries.
Schleswig (ancient forms Sliesthorp, Sliaswic, i.e. the town or bay of the Slia or Schlei) is a town of very remote origin, and seems to have been a trading place of considerable importance as early as the 9th century. It served as a medium of commercial intercourse between the North Sea and the Baltic, and was known to the Arabian geographers. The first Christian church in this district was built here by Ansgarius (d. 865), and it became the seat of a bishop about a century later. The town, which obtained civic rights in 1200, also became the seat of the dukes of Schleswig, but its commerce gradually dwindled owing to the rivalry of Lübeck, the numerous wars in which the district was involved, and the silting up of the Schlei. At the partition of 1544 the old chateau of Gottorp, originally built in 1160 for the bishop, became the residence of the Gottorp line of the Schleswig-Holstein family, which remained here till expelled by the Danish king Frederick IV. in 1713. From 1731 to 1846 it was the seat of the Danish governor of the duchies. In the wars of 1848 and 1864 Schleswig was an important strategical point on account of its proximity to the Dannewerk (q.v.) and was occupied by the different contending parties in turn. It has been the capital of Schleswig-Holstein since its incorporation by Prussia in 1864.
See Sach, Geschichte der Stadt Schleswig (Schleswig, 1875); and Jensen, Schleswig und Umgebung (Schleswig, 1905).