Belfort Montbéliard, who granted it a charter in 1307. Previously an Austrian possession, Belfort was transferred to France by the Treaty of Westphalia (1648), which ended the Thirty Years' War. The town's fortifications were extended and developed by the military architect Vauban for Louis XIV. Until 1871, Belfort was part of the "département" of Haut-Rhin, in Alsace. The Siege of Belfort (between 3 November 1870 and 18 February 1871) was successfully resisted until the garrison was ordered to surrender 21 days after the armistice between France and Prussia. The region was not annexed by Prussia like the rest of Alsace and
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