The Battle of Zusmarshausen was fought on 17 May 1648 between Bavarian-Imperial forces under von Holzappel and an allied Franco-Swedish army under the command of Carl Gustaf Wrangel and Turenne in the modern Augsburg district of Bavaria, Germany. The allied force emerged victorious, and the Imperial army was only rescued from annihilation by the stubborn rearguard fighting of Raimondo Montecuccoli and his cavalry.
Zusmarshausen was the last major battle of the war to be fought on German soil during the Thirty Years' War, and was also the largest battle (in terms of numbers of men involved; casualties were relatively light) to take place in the final three years of the war.
Background
By the late 1640s all the belligerents in the Thirty Years' War were exhausted by three decades of brutal fighting. Delegates had already convened in the Westphalian cities of Münster and Osnabrück to negotiate a peace treaty in 1646, but while the peace talks were in progress the opposing powers continued to jockey for position in order to improve their respective positions in the negotiations. The Swedes in particular were keen to win a final decisive victory against the Habsburg monarchy in order to secure territorial concessions within the Holy Roman Empire, and also to make the most of the war while it lasted by invading and plundering the rich Habsburg province of Bohemia, which was one of the few parts of the Empire to have been left largely untouched by the fighting so far.
Prelude
There were four armies involved in the Zusmarshausen campaign. On one side was the main Imperial field army of 10,000 men commanded by Peter Melander Graf von Holzappel, and a Bavarian force of 14,000 under . Opposing them was the 20,000-strong Swedish army under Carl Gustaf Wrangel, and a French army of 6,000 men commanded by Marshal Turenne, France's ablest general of the period.
Wrangel began the 1648 campaign by leaving the Swedish base at Bremen and marching south up the Weser, while simultaneously Turenne advanced from Alsace and marched north along the Rhine to meet him, the plan being to join forces on the River Main. Melander attempted to prevent his two enemies from combining, but the obstructionism of his ostensible ally Archbishop-Elector Ferdinand of Cologne hindered his movements, prohibiting the Westphalian army under General Lamboy to leave his territory, and Melander was eventually compelled to retreat to avoid being caught between the French and Swedish armies. Wrangel and Turenne were therefore able to join forces and push southeast into Franconia, forcing Melander to retreat into Bavaria, and specifically to Ulm, where he was subsequently joined by Gronsfeld's Bavarian troops.
In May the Franco-Swedish army advanced southward into Württemberg and then swung east to confront Melander and Gronsfeld in Bavaria. By this point disease and desertion had whittled the Imperial-Bavarians down to 16,000 men, and they therefore found themselves outnumbered by a ratio of around 3:2. Moreover, Melander was under orders from Emperor Ferdinand III not to risk his army, as a decisive defeat could have drastic consequences for the peace negotiations in Westphalia. He therefore decided to retreat again rather than confront Wrangel and Turenne, and ordered his troops to pull out of Ulm and march eastward toward Augsburg. To cover the retreat he detached a force of 2000 Croatian cavalry under Raimondo Montecuccoli to perform a rearguard action at a bridge over the Zusam river, in the village of Zusmarshausen.
Battle
The battle began at 7 AM on 17 May, when Montecuccoli's troops in Zusmarshausen came under attack from the Swedish vanguard. Montecuccoli held off the Swedish attacks for an hour before ordering his men to pull back eastward to the village of Herpfenried, where they mounted another stand. This time, however, a group of French cavalry managed to work their way round the southern side of Montecuccoli's position, threatening to cut him off from the rest of the Imperial-Bavarian army. Melander himself dashed back to rescue the rearguard, and in the resulting melee the general was shot in the chest and killed.
Montecuccoli managed to extricate his surviving men from Herpfenried around midday, and at 2 PM he rejoined Gronsfeld and the rest of the army, which had assumed a defensive position on the east bank of the Schmutter. Later that afternoon the French vanguard appeared and made a couple of probing attacks across the river, but they lacked the strength to mount a serious assault (most of the Franco-Swedish army was still strung out along the road from Ulm) and night fell before these forces could become available.