France’s victory at the Battle of Rocroi in May 1643 allowed France some operational flexibility on other fronts of the late Thirty Years War. French troops in Franche Comte (the “Free County” of Burgundy, Hapsburg territory and a frequent battleground of the war) could advance into the Holy Roman Empire to prevent Austrian and Catholic League reinforcements for the Army of Flanders, support German princes and electors allied with France, and exert some influence on the Swiss Confederacy which had so far sat out the Thirty Years War in relatively prosperous “heavily armed neutrality.” French marshal Josias von Rantzau, a Dane with a long and complicated history in the French court and commander of French troops in Franche Comte, crossed the Rhine that autumn and was reinforced with troops from Saxe-Weimar. Rantzau, a dandy of the French court and more known for his reckless bravery than any military acumen, immediately went into winter quarters in order to prepare for operations in the spring. The weather in late autumn was unseasonably cold, but the French “Army of Germany” was particularly vulnerable in winter quarters spread out in the villages around the Swabian town of Tuttlingen on the Danube. They were, however, within striking distance of next year’s target, the Electorate of Bavaria.

The Catholic Prince-elector of Bavaria, the venerable Maximillian I, spent the last 25 years in a mostly successful attempt preventing the Hapsburgs from subsuming the Catholic League. Bavaria and other Catholic electors in Germany were especially vulnerable to invasion and furthermore had enough problems internally with brigands (*spit*). He saw the Catholic League as a defensive alliance only, and its forces were not to be sent off wherever the Hapsburgs wished. However, a Franco-Weimarian army just across the border to the west was a threat that couldn’t be ignored. Bavaria had the second largest army in the Holy Roman Empire, but it was still small compared to Rantzau’s. Maximillian placed it in the hands of his extremely capable Lorrainer master of ordinance Franz von Mercy and his second Johann von Werth, one of the foremost Imperial cavalry commanders. Mercy and Werth were one of the conflicts most effective command teams and both of whom urged for an immediate attack on Rantzau’s exposed, unprepared, and dispersed army, no matter the weather.

As Rantzau’s 16,000 troops sat warm around their fires in the houses around Tuttlingen, Mercy and Werth gathered 15,000 troops mostly Lorrainers and Bavarians, but included small contingents of veteran Spanish troops from the Army of Flanders and Imperial troops from Austria. They were taking no chances after the defeat at Rocroi and if Rantzau was going to allow them to concentrate, who were they to not take advantage?

Rantzau’s sins did not end there though. His men were settled into winter quarters and most elements were not within supporting distance of each other. Rantzau assumed he would have sufficient time to assemble. If in the unlikely event that any Imperial army approached, his troops in the town of Möhringen to the northeast should have given ample warning.

However, Mercy and Werth didn’t approach as expected, whether down the Danube from the north east, or from Stuttgart in the north. They cut across the low mountains and lowland lakes and streams of the Upper Palatinate to the south east (i.e. through Hohenfels from east to west).
About mid-afternoon on 24 November 1643, Werth commenced the Battle of Tuttlingen with his assault on the outpost of Mühlingen. Surprise was complete and the French troops in the town were overrun in minutes. The French had no pickets out, few guards, and no pre-arranged assembly points. Rantzau and his senior officers were drunk and playing cards when they heard the first shots: those from Bavarian dragoons who scattered the only alert sentries in Tuttlingen: those of the artillery park. Before French could even hope to assemble any of their units, Mercy had already seized all of their cannon.

Rantzau sent riders out to concentrate his army on Tuttlingen but the regiments were so widely dispersed that the battle was over before it even began. Panicking, the vaunted French cavalry fled west as fast as they could ride. What infantry Rantzau was able to muster was subjected to bombardment by their own cannon turned manned by Bavarians. Weimarian cavalry from Mühlheim attempted come to their aid but were intercepted and destroyed. By nightfall, the resistance in Tuttlingen was surrounded and under merciless shelling.

Rantzau surrendered the next morning and the remaining isolated regiments were subsequently defeated in detail. The Weimarians in particular gave up almost immediately as there was little love for their French commander. That the battle lasted almost all of the next day had more to do with the French disorganization and distance between the cantonment areas than any serious resistance or maneuvering on the battlefield. What remained of France’s Army of Germany routed, and quickly fled back across the Rhine into Alsace.

The stinging defeat at Rocroi had been avenged: Mercy and Werth captured the entirety of the French command, all of the artillery and baggage and 7000 irreplaceable troops. The army of Saxe-Weimar ceased to exist and only a remnant of the French army from Franche Comte was available for the spring. However, there’s a reason we remember Rocroi today and not Tuttlingen. Rocroi had massive strategic effects, Tuttlingen did not. Bavaria gained only a temporary reprieve. Winter was there and the battle could not be immediately exploited. Moreover, Maximillian refused to lead the Catholic League on the offensive for the Hapsburgs in the spring of 1644. In 1645, the French again crossed the Rhine but little strategic gain for either side came from the various defeats and victories that year.