Westphalia as a small state within Germany in the form of a principality until 1918 and as a free state until 1946. This continues to influence the identity of its people who often distinguish themselves from neighboring regions such as East Westphalia. In addition to these historic, lingual and religious aspects, there are some regional differences in culture and mentality. That is why many of the citizens of North Rhine-Westphalia rather see themselves either as "Rhinelanders", "Westphalians" or "Lippers" rather than as "North Rhine-Westphalians". Westphalia is known for the 1648 Peace of Westphalia which ended the Thirty Years' War, as the
Hessian War Peace Congress mediated by Duke Ernest of Saxe-Gotha and which resulted in a unification and peace treaty that was sealed in April 1648, ahead of the Treaty of Westphalia itself. Before the Westphalian Peace Treaty, Cassel fought one last time against the imperial side, winning the Battle of Wevelinghoven in the Rhineland, together with other Protestant troops. Darmstadt, however, was not involved in this battle. Under the Unification Treaty between Cassel and Darmstadt, Upper Hesse was permanently divided. Darmstadt had to give up a significant part of Upper Hesse to Cassel, not least Marburg and other occupied territories, including the