Kingdom of France Spain and the Holy Roman Empire during the Thirty Years' War (1618–48) which had broken out in Germany. After the death of both king and cardinal, the Peace of Westphalia (1648) secured universal acceptance of Germany's political and religious fragmentation, but the Regency of Anne of Austria and her minister Cardinal Mazarin experienced a civil uprising known as the Fronde (1648–1653) which expanded into a Franco-Spanish War (1653–59). The Treaty of the Pyrenees (1659) formalised France's seizure (1642) of the Spanish territory of Roussillon after the crushing of the ephemeral Catalan Republic and ushered a short period of peace. 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