Introduction of Sonderborg
Seaside resort town on Swais Island , off the SE coast of Jutland , 17 mi NE of Flensburg. Part of the duchy of Schleswig, it developed around a 13th-century castle. After being deposed, Christian II was held prisoner here from 1532 to 1549. Christian III (1534-49) created the duchy of Sonderborg for his son from which the present Danish dynasty of Schleswig-Holstein- Sonderborg-Glucksburg is descended. The town was held by Prussia from 1864 to 1920. A museum here houses a collection of military objects, including many used in the battle at nearby Dybbol.