SLESWICK, an ancient and considerable town of Denmark, and capital of a duchy of the same name in the province of Gottorp, with a bishop's see, secularized in 1586. St Michael's church, which was the cathedral, is a magnificent structure, and has a chapter of noble ladies of the Protestant religion. This town was much more considerable than it is at present, it having suffered greatly by the wars of Germany. It is seated on the gulph of Sly, where there is a good harbour, 60 miles north-west of Lubeck, and 125 south-west of Copenhagen. E. Long. 9. 55. N. Lat. 54. 40.