The battle of Würzburg (3 September 1796) was the biggest victory won by the Archduke Charles in his successful campaign against the French invasion of Germany in 1796, and prevented General Jourdan from making a stand at any significant distance to the east of the Rhine. Over the course of the summer of 1796 General Jourdan and the Army of the Sambre-and-Meuse had advanced east from the Rhine, up the line of the Main, and by 20 August had reached the Naab, where they occupied the west bank while an Austrian army under General Wartensleben occupied the east bank. Further south the Army of the Rhine-and-Moselle under General Moreau had also advanced far into Germany, and on 24 August won a victory at Freidberg that allowed them to cross the River Lech and advance into Bavaria.
On the same day that Moreau won at Friedberg, Jourdan suffered a defeat at Amberg. The overall Austrian commander in Germany, the Archduke Charles, had decided to conduct a fighting retreat in the face of the two French armies, combine his own forces somewhere close to the Danube, and then turn on whichever French army was most vulnerable. In early August he decided that Jourdan would be his first target, and by 22 August he was approaching Jourdan's right-rear from the south-west. Jourdan attempted to retreat towards Nuremburg, but the Austrians intercepted him at Amberg, and he was forced to move north-west across the Franconian Switzerland (an upland area bounded on its south and east by the River Pegnitz) to reach the Main valley. The Archduke missed a number of chances to trap Jourdan in the hills, and on the Main around Bamberg, and on 31 August Jourdan reached Schweinfurt.
At this point Jourdan was safe. West of Schweinfurt the Main runs through two massive loops, each one twenty miles long from north to south. The Archduke was approaching the southern end of the first of those loops, around Würzburg. A good route led west from Schweinfurt across the open northern ends of the two loops, passing through Gemünder am Main on its way to Hanau, just to the east of Frankfort. If Jourdan had followed that route then the Archduke would have been unable to prevent him from joining up with the French forces besieging Mainz, and potentially retrieving the entire French campaign in Germany.
Instead of moving west Jourdan decided to remain on the upper Main, and attempt to defeat the Archduke in battle. Although this decision ended in failure, Jourdan did have two good reasons for making it. As he retreated west he received orders from the French Directory to remain on the Rednitz. Although he had already retreated some way west from that river, the orders did make it clear that Jourdan was not to retreat to the Rhine. Jourdan had also received a message from Moreau in which he had promised to conduct a campaign in Bavaria in an attempt to force the Archduke to send reinforcements south. This was a perfectly credible plan, for in the aftermath of his victory at Amberg and Moreau's victory at Friedburg the Archduke had sent a large contingent south to support General Latour. If Moreau's move was to have any chance of success, then Jourdan had to remain as far east as possible.
When Jourdan decided to move south he didn't expect to fight a major battle at Würzburg. He knew that Hotz had reached the bridge over the Main at Kitzingen, but didn't know that he had advanced west to Würzburg in some strength, or that the French garrison of the city had been forced to take refuge in the citadel. Hotz had six infantry battalions and nine cavalry squadrons at Würzburg. Two battalions and four squadrons were blockading the citadel, and the rest of his force was posted on the Galgenberg, a hill to the east of the city. As the French advanced south they found another Austrian force, under General Sztaray, at Kürnach, and forced them to retreat. Jourdan was so confident that he left General Lefebvre's division in Schweinfurt, to watch a small Austrian force further east up the Main.
By the end of 2 September the French were in position to the north of Würzburg. Bernadotte's division, under the temporary command of General Simon, was at Lengfeld, just outside the city, with some troops in a ravine that covers the village. Championnet was next, on the heights in front of Kürnach, four miles to the north-east. Grenier was another few miles to the north-east at Unterpleichfeld. Bonnaud with the cavalry reserve was behind the main French line, at Maidbronn. Collaud's division was dissolved and its men incorporated into the other divisions to bring them up to strength.
When he realised that the French were advancing south towards Würzburg, the Archduke Charles rushed reinforcements to the potential battlefield. On 2 September the Austrians threw a bridge across the Main at Schwarzach, six miles to the north of the existing bridge at Kitzinger. On the night of 2-3 September General Kray's division crossed the Main, and during the day General Wartensleben followed him. The Austrians were thus at least twice a strong as Jourdan believed when he planned his attack. The Austrian troops already across the Main had also moved into a strong position, with Holz on the Galgenberg, Sztaray to his east at Rottendorf and Lichtenstein a little further to the east.
Unaware of the reinforcements flooding towards him from the east, Jourdan prepared to attack Hotz and Sztaray. The French line ran north-east from the edge of Würzburg up to Unterpleichfeld. On the right Bernadotte's division, under General Simon, was to guard against any attack from Hotz. General Bonnaud, with the cavalry reserve, was to attack support the right, and also to move against the Prince of Lichtenstein. In the French centre Championnet, from the heights between Lengfeld and Kürnach, was to capture the woods of Estenfeld (north of Sztaray's position at Rottendorf). On the left Grenier was to advance south-east from Unterpleichfeld towards Seligenstadt, advance around what Jourdan believed was the Austrians' right wing and threaten their communications with the bridge at Kitzingen.
The battlefield was covered in fog from three in the morning until eleven o'clock, hiding Charles's reinforcements from Jourdan for even longer. The battle began with an Austrian attack. Sztaray and Hotz advanced into the ravines around Lengfeld, and drove the French out of the village. Simon counterattacked, and by noon had restored the situation.
The overall course of the battle was simple. Jourdan advanced south-west towards Würzburg, expecting to overwhelm the small Austrian force he believed was in the city. By the time the fighting started the Austrians actually had most of their army on or close to the battlefield, and their line stretched east from Würzburg, across the toe of the loop in the Main to Dettelbach and the bridge at Schwarzach, and it would later extend north from Dettelbach. Not only did the Austrians outnumber the French, but they were also concentrated on the French left. The French held their ground for some time, but late in the afternoon their line was finally broken and Jourdan was forced to order the retreat.
The battle was decided on the French left. When Jourdan saw that Championnet was in trouble in the centre, he ordered Gernier to attack south to support him. The Archduke moved Kray's cavalry to counter this, and Ney, at Oberpleichfeld at the extreme left of the French line was soon in danger of being outflanked. Jourdan realised a crisis was developing, and moved Bonnaud with the cavalry reserve and Klein with the light cavalry to his left. At about the same time the Archduke moved General Wartensleben's heavy cavalry to his right.
When Bonnaud arrived on the left he discovered that he was outnumbered by the Austrian cavalry, and decided to try and fight his way out of the danger. At first the French had some success, but the Austrian numbers soon told. They were able to mass their reserves against Bonnaud's centre, and make a charge that swept away the French lines.
Jourdan was forced to order a retreat. Grenier's division, on the left, was ordered to act as a rearguard, and made a stand on a line a little to the north of Oberpleichfeld. This gave Simon and Championnet time to escape, but Grenier's division suffered heavy losses in the fighting. General Kray caught up with them at Dipbach and Heiligenthal, and overwhelmed their left flank. Grenier was forced to retreat west into Gramschatz forest, six miles to the west, but four of his companies were caught half way at Opferbaum. They formed squares, but were eventually overwhelmed by the Austrian cavalry.
The Archduke had won a famous victory. The French lost around 6,000 men, four times as many as the Austrians, but the Archduke missed the chance to complete the destruction of Jourdan's army. Rather than send his cavalry on a vigorous pursuit of the retreating French he wasted time forming his army into two lines of battle, a move which gave Jourdan time to make good his escape.
The Archduke was able to block Jourdan's best line of retreat to the Main, preventing him from moving to Hanau. The French were instead forced to retreat to Schluchtern, close to Fulda, and then to the Lahn. On 9 September the French crossed the Lahn at Wetzlar and Giessen, where Jourdan decided to make another unsuccessful stand.