Illustrations of the War in Schleswig: the Ch?teau of Augustenburg, Island of Alsen, 1864. The Ch?teau of Augustenburg, on the Isle of Alsen..., formerly belonged to the Duke of Augustenburg, father of the Prince whose claim to be Duke of Schleswig-Holstein is a contingency of this war. The main three-winged building of Augustenborg Palace on Als Island, Denmark, was built from 1770 to 1776. From "Illustrated London News", 1864.