The battle of Hanau (30-31 October 1813) was an unsuccessful attempt to interfere with the French retreat after Leizpig, carried out by a Austro-Bavarian army that had moved up from southern Germany.
Somewhat ironically the only serious attempt to stop Napoleon was made by an army that hadn't been present at Leipzig, was made up of troops who until very recently had been opposing each other, and whose commander didn't realise he was about to try and stop Napoleon's entire army.
Bavaria had been one of Napoleon's allies in Germany, and at the start of the autumn campaign a Bavarian force under Count Wrede was posted on the River Inn, on the border between Bavaria and Austria, to watch for any Austrian invasion of southern Germany. The Bavarians changed sides on 8 October, and in an unusual move Wrede was given command of both armies on the Inn. This gave him a mixed force of 43,000 Bavarians and Austrians. Even before the battle of Leipzig, Wrede's force was moving north-west into central Germany, to threaten Napoleon's lines of communication back to France.
By late October Wrede was approaching Frankfurt on the Main. He believed that Napoleon's main army was somewhere to his north (perhaps heading for Coblenz), but he did detect some French troops heading his way, which he believed to be the left flank of the French army, perhaps 18,000-20,000 strong. On 29 October Sebastiani's cavalry occupied the defile at Gelnhausen, helping to convince Wrede that he was correct.
By the afternoon of 29 October Wrede was at Hanau, on the right bank of the Main east of Frankfort. The town sat between two rivers – the Main to the west and south and the Kinzig to the north. The Kinzig flows into the Main just to the west of the town. The Kinzig could only be crossed by a bridge to the north-west of Hanau (the route to Frankfort) or a bridge about a mile further to the east. The Lamboi forest came to within a mile of the north and the east of the town.
Napoleon was actually heading for Frankfurt along the main road from Erfurt, which ran along the northern bank of the Kinzig, then the northern bank of the Main. Wrede was thus putting himself in grave danger when he decided to post most of his army north of the Kinzig, to try and intercept the flank force he believed was heading his way.
Wrede's cause wasn't helped by his dreadful deployment. His right was posted to the south of the Kinzig, linked to the rest of his line by the Lamboi bridge. His centre was positioned between the Kinzig and the main road, with its back to the river. His left, which was made up of cavalry and 28 guns, was posted on the road itself, facing towards the forest.
At the start of the battle Wrede actually outnumbered his immediate opponents, 17,000 men under Victor, Macdonald and Sebastiani. The battle started with a clash between Victor and Wrede's outposts in the forest. By about noon the woods facing Wrede's centre were cleared. At about the same time Wrede realised that he was facing Napoleon (hearing cries of 'Vive l'empereur'), but he decided to fight on. He did try and reinforce the link between his right and the rest of his army by moving a brigade from his right to protect the bridge.
Napoleon decided to attack Wrede's left, on the main road. Drouot, his chief of artillery, had found a track running through the woods to the north of the main road, and believed that it was good enough for artillery. By 3pm two battalions of Grenadiers of the Old Guard had cleared the woods opposite Wrede's left, and Drouot was able to build up a battery of fifty guns. The 2nd Cavalry Corps (Sebastiani) and the Guard heavy cavalry drew up behind the guns.
Drouot's guns quickly silenced Wrede's smaller battery. The French cavalry then attacked, and drove off Wrede's cavalry, on his left. Wrede's centre was then attacked from two sides, with Drouot's guns firing on it from one direction and the French cavalry attacking it from the left.
Wrede's centre didn't hold for long, and was then forced to retreat. This was a difficult maneuver with the river at its back. The infantry had to try and escape to its left, along the river bank, and suffered heavy losses during the move. The right-most three battalions of the centre were cut off and lost several hundred men in the river. The survivors from the left and centre rallied at Gross Auenheim.
Wrede's right also suffered. Wrede had called up a second brigade from his right to try and restore the situation. This brigade found the first brigade already retreating, to avoid the fate of the centre. The new troops counterattacked and forced the French back into the forest, but the French counterattacked in turn and both of Wrede's brigades were forced to try and escape across the single bridge.
On the night of 30-31 October Wrede formed a new line on the south bank of the Kinzig. His left was in Hanau, his right was facing the Lamboi bridge and his centre ran along the Aschaffenburg road.
The battle continued on 31 October, but on the south bank of the Kinzig. The bulk of Napoleon's army passed by on the north bank, heading for Frankfurt and then on to Mainz.
Napoleon left III Corps (Souham), VI Corps (Marmont) and IV Corps (Bertrand) to watch Wrede. At 2am on 31 October French artillery began a bombardment of Hanau, which was evacuated by Wrede. Bertrand was able to occupy the town without resistance at 8am.
For most of the day little happened around Hanau. Bertrand held the town, and Marmont watched the Lamboi bridge. By 3pm the rest of the French army had passed by, and Marmont withdrew with III and VI Corps. Bertrand remained in place to act as a rearguard.
With most of the French army gone, Wrede attacked the Lamboi bridge and Hanau. The attack on the Lamboi bridge failed, but his troops were able to take Hanau. Wrede was injured in the attack on Hanau.
The French withdrew to the Kiznig bridge north-west of Hanau. Wrede's men attacked this bridge, but were repulsed. Wrede was now behind the French, and had suffered heavy losses without achieving anything.
Wrede lost 9,250 men between 28 October, when the first skirmishes began, and 31 October, including 3,400 Austrians and 2,900 Bavarians during the battle itself . The French lost few men in the battle, but the Allies captured around 10,000 stragglers (including 5 generals in the same period). Although Napoleon had succesfull managed to extract part of his army from Leipzig, it was now losing its discipline as the retreat continued.
On 2 November the main body of the French army reached Frankfurt and safety, with their rear base at Mainz only 20 miles away. The theatre of war was about to move from Germany to France, and this time the Allies didn’t give Napoleon time to raise a fresh army, invading early in 1814.