International relations, 1648–1814 and cultural achievement. Historian Frederick Nussbaum says it was: The worst came during the Thirty Years' War, 1618–1648, which had an extremely negative impact on the civilian population of Germany and surrounding areas, with massive loss of life and disruption of the economy and society. Scholars taking a "realist" perspective on wars and diplomacy have emphasized the Peace of Westphalia (1648) as a dividing line. It ended the Thirty Years War (1618–1648), where religion and ideology had been powerful motivating forces for warfare. Westphalia, in the realist view, ushered in a new international system of sovereign states of roughly equal
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