Napoleon was forced to retreat to the Rhine after his defeat at Leipzig on 16-19 October 1813. His retreat ‘was on the whole a remarkably successful operation’ in the opinion of David Chandler. The Coalition armies pursued cautiously, and the French were moving along their main line of communications, enabling them to resupply and re-equip as they retired.
About 100,000 French troops reached the large supply base of Erfurt on 23 October. They were issued with new equipment, but had to resume the retreat the next day because the Coalition forces were close behind. The French continued to lose many tired, sick and hungry stragglers on the retreat.
France’s erstwhile ally Bavaria had changed sides and joined the Coalition against France on 14 October. On 30 October, following two days of skirmishing, 43,000 Austrians and Bavarians under the command of the Bavarian General Karl Phillip von Wrede attempted to block Napoleon’s retreat at Hanau, a few miles east of Frankfurt-on-Main, the next supply base on the French line of retreat.
Wrede believed wrongly that the French main body was further north, on the road towards Coblenz, so thought that he faced only 20,000 men. Wrede took up a position described by F. Lorraine Petre as ‘hopelessly bad.’
The River Kinzig flowed behind the Austro-Bavarian centre before turning to divide the right from the rest of the army. They could cross only at the Lamboi bridge because the river was swollen by the autumn rains. A thick forest allowed the French to approach close to the enemy without being spotted.
Napoleon had only about 17,000 men available at first, but attacked the Austro-Bavarian left flank. He was able to obtain a local superiority because of the terrain. Wrede’s left flank, consisting mostly of cavalry, was driven off the field by French cavalry and artillery.
The centre resisted for a little longer, but then had to retreat because its left flank was threatened by the victorious French cavalry. Casualties were increased because the river obstructed the retreat. Wrede brought reinforcements from his right to the centre, but they were forced to retreat back over the Lamboi bridge, and hundreds were drowned.
Napoleon, having driven Wrede off, continued his retreat. The French bombarded Hanau at 2 am on 31 October. Wrede evacuated it, and the French occupied it at 8 am. Wrede launched an unsuccessful counter attack, in which he himself was wounded, and the French passed through Hanau on their way to Frankfurt.
Wrede’s army lost 9,250 men killed and wounded at Hanau. French combat casualties were far lower, but the Coalition captured five French generals, 280 officers and 10,000 men from 28-31 October.
The French reached Frankfurt, less than 20 miles from the Rhine, on 2 November. About 70,000 organised troops and 40,000 stragglers made it across the Rhine. Nearly 300,000 men had been lost so far in the campaign. Another 100,000 in isolated garrisons across Germany were effectively lost.
On 11 November Marshal Laurent St Cyr accepted terms for the surrender of Dresden that would allow the garrison to return to France provided that they did not take part in the war. However, Prince Karl Philip zu Schwarzenberg, the Coalition commander, refused to ratify the agreement, leaving St Cyr little choice other than unconditional surrender. The same thing happened at Danzig and Torgau.
Napoleon had suffered an enormous defeat for the second year running. He failed to learn one of the lessons of the failure of his 1812 Russian Campaign, which was that his army was too big for one man to co-ordinate with the communications of the day. Before the decisive defeat at Leipzig, Napoleon had won all of the battles where he was in personal command, Lützen, Bautzen and Dresden, but his subordinates had lost the other three significant battles of the campaign.
The marshals had to operate more independently than most were capable of. Napoleon should be blamed for failing to train them to do so, and did not make the most of his better commanders. Louis Davout, commanding the Hamburg garrison, and André Masséna, not employed after his defeat at Fuentes de Oñoro in 1811, would surely have done better than Nicolas Oudinot, beaten at Gross Beeren, Jacques MacDonald, beaten at the Katzbach or Michel Ney, beaten at Dennewitz.
Napoleon came up with impressive plans throughout the campaign, but his army was no longer able to execute them successfully. His inexperienced troops were tired and hungry because they were short of supplies. Napoleon also lacked good intelligence of the enemy’s strength and movements because the huge horse casualties of 1812 left him short of the cavalry needed to carry out reconnaissance.
The Emperor made key mistakes during the campaign. He should not have agreed to an armistice after his victory at Bautzen, since the opposing Coalition was building up its forces faster than he could. He might have won at Leipzig if he had not broken his rule of concentrating all available forces at the decisive point by leaving a substantial garrison at Dresden.
In the Autumn campaign the Coalition stuck successfully to its Trachenberg Plan of retreating when facing battle with Napoleon himself, whilst attempting to threaten his lines of supply and defeat isolated French corps, until it was able to concentrate all its forces at Leipzig and win a decisive victory.
 D. Chandler, The Campaigns of Napoleon (London: Weidenfeld & Nicolson, 1966), p. 937.
 Troop strengths are from Ibid., pp. 937-38.
 F. L. Petre, Napoleon’s Last Campaign in Germany, 1813 (London: Arms and Armour Press, 1974, first published 1912), p. 391.