1810: Napoleon having designated Davout’s Corps to furnish the occupation troops for the north of Germany, the regiments left their cantonments on the 1st February 1810 and set off for Magdeburg, where they were to be fed and paid by the King of Westphalia. All of the army, with the exception of the three divisions of Gudin, Morand, and Friant, and two cavalry divisions, returned to France. These troops took the name of the Army of Germany. In April, Marshal Davout established his residence at Hamburg, and his divisions were divided between Hanover, the Hanseatic Towns, Magdeburg and the Elbe. Gudin’s Division had to guard Hanover, it was increased to five regiments by the addition of a regiment from St-Hilaire’s division. The regiments were formed into four battalions; the 21st was placed at Halberstadt. In June it went to occupy Brunswick, where it remained until the end of the year 1810.
In January 1811, the Regiment went to take up garrison duties at Magdeburg. For the formation of the fourth battalions, the Emperor had prescribed the assignment of the conscripts already formed at the depot. The depot then became the fifth battalion and received the young soldiers of the conscription of 1811 that were being called to the colours. In March, they formed the sixth battalion, the fifth remaining as the depot, and to speed the organisation of this battalion, and not distract the cadres at the depot by assigning them to conduct the recruits to the field battalions, the new men were ordered straight to Magdeburg. In May, however, Napoleon countermanded the departure of the fourth and sixth battalions, and decided that the recruits should be formed at the depot. It was not until the August, when their military instruction was completed, that they were directed to Magdeburg and the Regiment counted five field battalions, each battalion had some 840 men present under arms.
The Emperor had ordered, in April, the formation of three Corps of observation, on the Elbe, on the Rhine, and in Italy. The 21st, brought together, was made part of the Third Division of the Corps of Obsevation of the Elbe, under the orders of Marshal Davout.
At the begining of 1811, the Czar of Russia, contrary to the treaty of Continental Blockade, had re-opened his ports to the commerce of England, closed the Russian ports to the industrial products of France, and created an army of 80,000 men, to ensure the execution of these measures. Napoleon wanted the ukase of the Czar to be solemnly withdrawn, but the dignity of this sovereign could not lend itself to such a concession, and it was necessary once more to prepare for war.