The siege of Hamburg (3 December 1813-27 May 1814) was the last phase in Davout's year long occupation of Hamburg, and lasted until after Napoleon's first abdication.
At the start of 1813 Hamburg was officially part of France, along with a sizable strip of northern Germany. Possession of the city was vital for Napoleon, who intended to campaign east of the Elbe. If Hamburg fell, then the Allies would be able to get across the lower Elbe, and the entire campaign plan would be endangered.
Unfortunately for Napoleon, General Carra St Cyr, who commanded at Hamburg, believed that he faced two threats – a large Russian army, and the danger of an uprising within the city, and decided that he couldn't hold the city with only 3,000 men. On 12 March Carra St. Cyr retreated from Hamburg to Bremen, taking 100,000 francs from the city treasury with him.
Carra St. Cyr had misjudged the situation. The only Allied troops in the area were some German irregulars, but after the French fled they were able to take the city. A Russian free corps soon arrived, and was welcomed with great enthusiasm. Hamburg was then held by a mixed force of local militia and Cossacks for the next two and a half months. During this period the Allies were unable to take advantage of the situation, and the main campaign took place much further to the south, in Saxony.
During the Spring Campaign of 1813 Marshal Davout was given the task of retaking Hamburg. He gave the task to Vandamme, along with two divisions. Vandamme recaptured the city on 30 May, and was then given command of I Corps in the main army in Saxony.
Davout was based at Hamburg for the rest of the war. He commanded XIII Corps, part of the new army raised by Napoleon after the disaster in Russia. During the rest of the Spring campaign his main task was the organisation of his new command.
At the start of the Autumn campaign Davout had around 35,000 men around Hamburg. His immediate opponent was General Ludwig Graf von Wallmoden-Gimborn, an Austrian officer in the Russian army, who had 25,000 troops, including many newly raised irregulars. Davout's main task in the autumn was to support Napoleon's two attempts to take Berlin. The first, under Oudinot, ended in defeat at Grossbeeren (23 August 1813). The second, under Marshal Ney, did even worse, and Ney was defeated at Dennewitz (6 September), only a couple of days after setting off from the Elbe.
Davout supported these attacks on Berlin by advancing east out of Hamburg. On 18 August his troops left their cantonments around the city and advanced up the Elbe. That evening a battalion from the 30th Line reached Lauenburg, 22 miles up the Elbe, which at this point ran west/ north-west towards Hamburg. The Allies had two battalions of Lützow's corps at Lauenburg, but overnight they abandoned this position and retreated to Wellahn. The French followed up, and reached Boizenburg, a few miles further east up the river.
On 20 August the French attacked the Allies at Boizenburg (Lutzow's men and Tettenborn's Cossacks). They retreated north to Zarrentin and joined up with a Swedish force under General Vegesack. On the same day the French advanced towards Wittenburg, six mile to the east of Zarrentin. This move threatened to cut the Allies off from the Baltic. Walmoden retreated further east, and posted his left and centre around Grabow (about 25 miles to the south-east of Wittenburg). Vegesack, with the Allied right, was dangerously isolated at Grevesmühlen, close to the Baltic.
On 23 August the French, reinforced by a Danish division under the Prince of Hesse were at Wittenberg, and on 24 August Davout reached Schwerin, 15 miles to the east/ north-east of Wittenberg and well to the north of Walmoden's position at Grabow.
On 25 August Davout sent Loison's division to Wismar, on the Baltic coast, in an attempt to cut off Vegesack, but the Allied right escaped from the trap and retreated to Rostock.
On 2 September Davout learnt of the defeat at Grossbeeren, just over a week earlier. He realised that his advanced positions were now dangerously exposed, and ordered Loison to evacuate Wismar. Loison and the Danes moved west to Schonberg, just to the east of Lübeck. At that point the Danes and French split. The Danes left a garrison in Lübeck, and retreated another twenty miles to Oldesloe on the River Trave. Loison didn't move quite as far, and took up a position around Ratzeburg, twenty file miles to the west of Schwerin. The Allied followed up – Walmoden moved to Schwerin, and Vegesack to Grevismulhen.
It was increasingly clear that Hamburg might soon be attacked. Davout improved the defences of the city, and gathered supplies.
Davout conducted an active defence against the advancing Allies, slowing down their progress. This didn't always go according to plan. In September some German Landsturm captured a message that revealed that an isolated force under General Marc-Nicholas-Louis Pecheux was heading up the Elbe to check the banks. On 16 September 1813 part of the Russo-German Legion, led on the day by Clausewitz, forced Pécheux to retreat into Hamburg (combat of the Göhrde).
On 13 November Davout abandoned his advanced position at Ratzeburg, and retreated across the Stecknitz (a right bank tributary of the Elbe, which flows south into the river at Lauenburg), aware that more Allied forces would be heading his way after Napoleon's defeat at Leipzig.
On 20 November Bernadotte left Hanover to join the forces attacking Hamburg. He detached Woronsoff's and Stroganov's Russian corps from the main force, and ordered them to sweep the left bank of the Elbe. Strogonov assaulted Stade, twenty one miles to the west of the city. The garrison resisted a first assault, but evacuated the place overnight and retreated to Gluckstadt, ten miles to the north on the right bank. Stroganov then relieved Woronsoff outside Harburg (on the south bank of the Elbe opposite Hamburg), leaving Woronsoff free to join up with the Swedish army at Botzenburg.
Bernadotte was prepared to attack Davout in his new position behind the Stecknitz, but on the night of 1-2 December Davout withdrew behind the Bille, another tributary ten miles to the east of the city and then withdrew into Hamburg.
The Allies finally surrounded Hamburg on 3 December 1813. Davout had around 34,000 men to oppose an Allied force under the Russian General Bennigsen and Bernadotte, now the Crown Prince of Sweden. They were later joined by the Russian General Dokhturov, who arrived at Hamburg after taking part in the siege of Magdeburg, and remained there until the end of the war.
The siege took place the middle of a harsh winter. Davout was forced to melt ice for water, and expelled 25,00 civilians from the city to save on food.
In February 1814 the Allies carried out a series of assaults on the city. Each of these failed, at least in part because of Davout's impressive leadership, and ability to be at the right place to deal with any crisis that appeared.
On 23 March Davout even launched a sortie in order to capture supplies. The sortie was launched from the Fort of Haarburg, south of the Elbe (the main city being on the north bank), and caught the Allies by surprise.
Although Davout's exploits at Hamburg were impressive, his presence here meant that he wasn't available for the defence of France of 1814. In early April Napoleon abdicated for the first time. General Bennigsen, still in command of the siege, issued two demands for surrender, but Davout refused, on the grounds that he could only accept orders from Napoleon.
On 11 May 1814 General Maurice Etienne Gérard arrived at Hamburg with orders to surrender the city from King Louis's War Minister. Even then Davout delayed the capitulation until 27 May, when 26,000 men left the city. Given the length of the siege, and the heavy losses suffered in shorter sieges further east, Davout had performed well to keep his force largely intact, but his efforts weren't appreciated by the restored Bourbons, and he was ordered to go to his home at Savigny-Sur-Orge, where he remained until Napoleon returned from exile.