[Ennath]

April 25, 1626
Battle of DessauBridge

In March 1626, Christian IV of Denmark committed his country to the faltering Protestant cause in Germany. However, his dwindling funds increased his dependence on unreliable allies and made it harder to impose his authority on the generals who joined him, notably the veteran mercenary Ernst von Mansfeld. Christian concentrated his main army of 20,000 at Wolfenbuttel to keep the Imperial and Catholic League armies of Wallenstein and Tilly, respectively, divided. Wallenstein was at Halberstadt to the southeast with about the same number of troops, while Tilly, with slightly fewer, stood on the Weser to the west with the Harz Mountains between them.

Christian sent Johann Ernst of Weimar with a small detachment across the Weser to distract Tilly and try to capture Osnabruck. Duke Christian of Brunswick mustered at Göttingen ready to push into Hesse where Count Philipp Reinhard of Solms had mustered 4000 peasants. Aware that the Landgrave of Hesse would probably join them if they got through, Tilly wanted to take Göttingen and nearby towns to secure the frontier of Hesse, which continued to pay a large part of his army.

Tilly’s refusal to cross the mountains to join Wallenstein disheartened the imperial commander, who tendered his resignation no less than 6 times in February and March, in protest at the failure to provide funds for his army. Wallenstein was also concerned at a new threat to his forward base from Mansfeld, who now had 12,000 men at Lauenburg on the Elbe ready to invade Brandenburg and turn his flank. Emperor Ferdinand had no desire to spread the war into Upper Saxony and ordered Wallenstein to remain west of the Elbe, where he began operations against Duke Christian. He was forced to turn back in February when Mansfeld advanced along the Elbe through Brandenburg, while a small Danish corps under Gen. Fuchs followed on the far bank. Mansfeld announced that he was coming to liberate Magdeburg and began occupying Anhalt territory east of the river. Wallenstein soon chased away Fuchs, but learned that Mansfeld was threatening his outpost, under Johann von Aldringen, at Rosslau, near Dessau, which guarded the only permanent bridge between Magdeburg and Dresden. If this fell, Mansfeld could disrupt supplies from Bohemia to the imperial army. Not for the last time, there was talk in Vienna of replacing Wallenstein.

In April, both sides converged on Dessau. Aldringen arrived first, creating a strong position centered on heavy artillery. Due to Wallenstein's inexperience, Mansfeld was overly confident and underestimated his enemy. He increased his pressure on Aldringen from April 12; Wallenstein rushed reinforcements, arriving himself with the main army on April 24, bringing his force to 14,000 men. Mansfeld had bitten off too much, having quarreled with Fuchs, who was too far north to help. With only 7000 men, he was too weak to take the imperial positions. He gambled everything on a final assault at 6 AM on April 25, not realizing the Wallenstein had concealed troops in a wood to the east. These counterattacked just as Mansfeld’s assault was flagging. Mansfeld’s cavalry fled downstream to Havelburg, abandoning the infantry, who surrendered. Mansfeld lost 4000 men, while the imperial army lost 2000.

Mansfeld was able to rebuild his army to a strength of 7000, which gave him an army similar in size to the one he had lost half of at Dessau. His rally did not last long as he died soon after. Duke Christian died on June 26, bringing his operations to a halt. The Danish army retreated into Upper Silesia. King Christian IV and his army were destroyed by Count Tilly in the Battle of Lutter, which left Tilly with the lands of Holstein, Jutland, and Schleswig.