Battle of Dessau Bridge The Battle of Dessau Bridge ( ) was a significant battle of the Thirty Years ' War between Danish Protestants and the Imperial German Catholic forces on the Elbe River outside of Dessau , Germany on April 25 , 1626 . This battle was an attempt by Ernst von Mansfeld to cross the Dessau Bridge in order to invade the headquarters of the Imperial German army in Magdeburg , Germany . The Dessau bridge was the only land access between Magdeburg and Dresden , which made it difficult for the Danes to advance . The Count of Tilly wanted control of the bridge in order to prevent King Christian IV of Denmark from having access to Cassell and to protect the Lower Saxon Circle . The Imperial German forces of Albrecht von Wallenstein handily defeated the Protestant forces of Ernst von Mansfeld in this battle . Preparation for Battle . Albrecht von Wallenstein began his preparation in October and November of 1625 by settling in the Halberstadt - Aschersleben area and extending its borders . Wallenstein and the growing Imperial German army were informed of the approach of Mansfeld and his Danish army . King Christian IV of Denmark had formally entered Denmark into the Thirty Years War . As Mansfeld and his army was commanded to approach Albrecht von Wallenstein at the Dessau Bridge , King Christian IV of Denmark and ally Christian of Brunswick were commanded fight the Catholic army of the Count of Tilly in Upper Austria . Although Christian of Brunswick ' s defeats at Fleurus , Höchst in 1622 , and the Battle of Stadtlohn in 1623 were victorious , the battles diminished his force . Christian of Brunswick and his peasant Protestant army , backing the army of King Christian of Denmark , was soon eliminated by the Catholics due to the weakness of his army and lack of a supporting army from Landgrave when moving into Hesse . Part of the Imperial German army , under the command of Johann von Aldringen , had time to prepare heavy artillery and troops for any Protestant threat advancing down the Elbe . Wallenstein and the Imperial Catholic league marched to Dessau , where Mansfeld and the Protestant army would inevitably try to cross in order to reach Magdeburg and the German Catholic League headquarters in Aschersleben . In Vienna , there was talk of Wallenstein ' s deposition from his army and replacement by the Italian , Count Collalto , an expert in the art of mercenary leadership . Battle and Outcome . In April of 1625 , Mansfeld and his army moved quick as possible to Dessau as well as Wallenstein and the Imperial German army . Aldringen and his men arrived first , thus allowing them to form their " death trap " at the Dessau Bridge , deploying the heavy artillery which they possessed . Wallenstein ' s inexperience had Mansfeld overly confident and underestimated as they approached . Mansfeld was not aware that they were soon to face the most powerful and deceivingly large army along the river bank of the Elbe . On April 25 , the battle began and the troops of Aldringen held off Mansfeld and his troops as they attempted to push across the bridge and river . The Catholic League was in soon in heavy force by the arrival of Wallenstein and troops . Mansfeld and his troops were completely overpowered . As soon as nearly half of Mansfeld ' s army was destroyed , the Danes retreated to Silesia . Mansfeld was able to rebuild his army with the help from Johann Ernst and an army of 7 , 000 , which gave him a similar sized army which he had lost half of at Dessau . His rally did not last long as he died outside of a village in Sarajevo soon before his ally , Johann von Ernst . The Danish Protestant army fell apart and retreated into Upper Silesia . Christian IV of Denmark and his army were destroyed by the Count of Tilly in the Battle of Lutter , which left Tilly with the lands of Holstein , Jutland , and Schleswig .