King Christian IX of Denmark signs the November constitution that declares Schleswig to be part of Denmark. This is seen by the German Confederation as a violation of the London Protocol and leads to the German–Danish war of 1864.

Christian IX was King of Denmark from 15 November 1863 until his death in 1906. From 1863 to 1864, he was concurrently Duke of Schleswig, Holstein and Lauenburg. He became one of the most influential monarchs of 19th-century Europe through the dynastic marriages of his children, earning the…