Christian IX signs the so-called November Constitution establishing a shared law of succession and a common parliament for both Schleswig and Denmark. This is seen by the German Confederation as a violation of the 1852 London Protocol.
24 December – Saxon and Hanoverian troops marched into Holstein on behalf of the Confederation. Supported by the German soldiers and by loyal Holsteiners, Frederick VIII, Duke of Schleswig-Holstein took control of the government of Holstein.