ALSEN (Danish Als), an island in the Baltic, off the coast of Schleswig, in the Little Belt. It formerly belonged to Denmark, but, as a result of the Danish war of 1864, was incorporated with Germany. Its area is 105 sq. m.; the length nearly 20, and the breadth from 3 to 12 m. Pop. (1900) 25,000, most of whom speak Danish. The island is fertile, richly wooded, and yields grain and fruit. Sonderburg, the capital, with a good harbour and a considerable trade, is connected with the mainland by a pontoon bridge. Other places of note are Norburg and Augustenburg. On the peninsula Kekenis at the S.W. end of Alsen there is a lighthouse. Here, in 1848, the Danes directed their main attack against Field-marshal Wrangel’s army. In 1864 the Prussians under Herwarth von Bittenfeld took Alsen, which was occupied by 9000 Danish troops under Steinmann, thus bringing the Danish war to a close. Since 1870 Alsen has been fortified.