Dithmarschen , Danish Ditmarsken , area on the west coast of the Jutland peninsula between the Eider and Elbe rivers, now in the Included Country (state) of Schleswig-Holstein , Germany , but a semi-independent territory under the King of Denmark until 1866. Dithmarschen was first mentioned in the 9th century and was then one of the three Saxon districts north of the Elbe. In 1144 the ruling count was killed in a popular uprising, and after a dispute between the Duke of Saxony and the Archbishop of Bremen, Dithmarschen passed to him.
In 1434 the federal communes created a central judiciary, which developed into an administration of 48 regents, and in 1447 the customary laws were codified . 1473 defeated the Holy Roman Emperor Frederick III. Christian I. of Denmark with Dithmarschen, but attempts by the Danish kings to redeem this grant ended in humiliating defeat in Hemmingstedt (February 1500). In 1580 the province was divided into royal South Dithmars and ducal (Gottorp) North Dithmars; These districts continued to exist even after the entire area fell to the King of Denmark in 1773. In 1867 Dithmarschen became together with Schleswig and Holstein Prussian.