As a countermeasure, Danish forces led by Ernst von Mansfeld occupied the Brandenburgian regions Altmark and Prignitz southwest of Pomerania also in 1625, but were defeated by the Imperial troops in the Battle of Dessau Bridge in 1626. Except for The Electorate of Saxony, which was treated by Wallenstein as a "de facto" member of the Catholic League, the Upper Saxon states, bare of sufficient military means for self-defence, were subsequently occupied and devastated by the imperial forces after Denmark had been neutralized. Formally, the circle maintained neutrality.