シュレースヴィヒ＝ホルシュタイン問題
The palace became the chief seat of their line which used the name Augustenborg as its branch name. Later, a Danish king made the head of that line specifically Duke of Augustenborg. They grew in relative prominence in late 18th century, and in the 19th century Schleswig-Holstein Question, being the symbols of pro-German nationalistic movement in Schleswig-Holstein. The area was annexed by Prussia in 1864 from Denmark, but was returned in 1920 following a plebiscite.