In the Thirty Years' War both the city of Halle and the Moritzburg time and again attracted troops. In October 1625 Wallenstein occupied town and fortress. After the defeat at Breitenfeld, the Count of Tilly moved, pursued by the Swedes, to the Moritzburg as a first retreat. In September 1631 the Swedish king Gustavus Adolphus appeared before Halle and could peacefully occupy it for a longer period. Following the Peace of Prague in 1635 the Emperor acknowledged the Duke of Saxony-Weißenfels as the new Administrator.