Dominions of Sweden German principalities, the Swedish kings in their roles as princes and dukes, or "Reichsfürsten", of the Holy Roman Empire took part in the German diets from 1648 until the dissolution of the Holy Roman Empire in 1806. Following the Thirty Years' War, the Peace of Westphalia in 1648 assigned to Sweden the two bishoprics of Bremen-Verden, with the exclave of Wildeshausen. All of them were ceded to Hanover in the peace treaty of 1719. By the Peace of Westphalia in 1648 Sweden received Swedish Pomerania, situated along the German Baltic Sea coast. The whole Duchy of Pomerania was under Swedish
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