The battle of The Geisberg or Wissembourg (26 December 1793) was a French victory that forced the Austrians and Prussians to abandon their last foothold in Alsace. On 13 October General Würmser's Austrians had forced their way through the Lines of Wissembourg, a series of fortifications that protected the northern border of Alsace. For a couple of weeks it looked as if the Allies might conquer Alsace.
The French Directory responded by appointing General Hoche to command the Army of the Moselle and General Pichegru to command the Army of the Rhine and by rushing reinforcements to the area. The immediate crisis soon passed, mostly because the Prussians and the Austrians failed to cooperate. While Würmser pressed on towards Strasbourg the Prussians (under the Duke of Brunswick) remained on Saar. The Allied armies were separated by the northern end of the Vosges mountains (now the Palatinate Forest), and because of the slow Prussian advance were no longer level with each other.
General Hoche soon seized the initiative. An attempt to catch the Prussians in mid November failed, but Brunswick decided to retreat north to Kaiserslautern. Hoche then attempted to attack Kaiserslautern (28-30 November) but was defeated and suffered heavy losses.
After this setback Hoche decided to turn east to attack Würmser's exposed right flank. 12,000 men from the Army of the Moselle crossed the Vosges, and on 18-22 December helped Pichegru force the Austrians out of their defensive position on the Moder (battle of Froeschwiller).
Würmser retreated back to the Lines of Wissembourg, occupying the French defences on 24 December. The Austrians were now spread out between Lauterbourg on the Rhine and Wissembourg. The Prussians then took over the line and held the Upper Lauter as it entered the mountains.
On 24 December Hoche was appointed commander-in-chief of the combined armies of the Rhine and the Moselle. He decided to launch an attack on the Austrian lines on the morning of 26 December.
After the defeat at Froeschwiller the Allied commanders had come together and had also decided to go onto the offensive. The Allied attack was also to begin on 26 December. On the day the French moved first, catching some of the Austrian forces out of their defences but before they were ready to attack.
One French column, under General Desaix, attacked along the Rhine towards Lauterbourg. Next in line was General Michaud, who attacked Schleithal, half way between the river and Wissembourg. Both of these attacks were successful, but the main thrust of the French attack came further west, at Wissembourg.
Here Hoche caught one Austrian detachment out of position south of the Geisberg. The Austrians were pushed back into the defences on the heights of Geisberg, but were then forced out by a French bayonet charge and retreated back towards Wissembourg in some disarray. The situation was saved by the Duke of Brunswick, who at the start of the attack was at Pigeonnier, just to the west of Wissembourg. He took command of the Austrian reserves and with the support of some Prussian troops managed to delay the French. This gave the Austrians time to mount an orderly retreat.
On the day after the battle the French reoccupied the Lines of Wissembourg. The Prussians retreated to Bergzabern, and the Austrians to Germersheim on the Rhine. Brunswick attempted to persuade Würmser to continue the campaign, but on 30 December the Austrians crossed the Rhine to Philippsburg. The Prussians were forced to retreat north to Mainz, where they went into winter quarters. Hoche had successfully expelled the Allies from French soil.