The Three Year War, which lasted from 1848 to 1850, was partly a civil war between different parts of the Danish United Monarchy and partly a conflict between Denmark and the German states, which supported the Holstein secession-movement.

The Three Year War was ultimately a result of the national-liberal movements, which all over Europe clamored for national independence.

Several pivotal battles took place during the Three Year War, among them the Battle of Isted Moor, which is the greatest battle in Danish history.

The Three Year War ended when the great powers of Europe signed an agreement, which maintained the status quo of the involved parties.