The Russian–German Legion was a military unit set up in 1812 by the banished Graf Peter of Oldenburg on the instigation of Tsar Alexander I of Russia.
Its first commander was Oberst von Arentsschild, and it was formed from German prisoners and deserters left behind in Russia after the French invasion earlier that year.
It was formed to fight against Napoleon as part of the Imperial Russian army but was paid by Russia's ally, Great Britain. Ernst Moritz Arndt, the private secretary to the pro-Russian Heinrich Friedrich Karl vom und zum Stein, acted as head propagandist to entrants to the Legion. He stayed in Saint Petersburg from 1812 onwards and attracted entrants by winning them over to fight to liberate Germany from its French occupying forces.
The Russian–German Legion was 9,379 strong in total and consisted of eight infantry battalions, one company of Jägers, two regiments of hussars and two batteries of horse artillery.
Carl von Clausewitz was among notable soldiers of the Legion.
On 6 July 1812, after the contract of Peterswaldau, Great Britain received the task of providing for the Russian–German Legion and thus acquired the right to determine how and where it was to be deployed. Ludwig von Wallmoden-Gimborn was now put in command, and the Legion ventured to the lower Elbe, fought at Mecklenburg and Holstein, attacked Harburg and marched far as the Netherlands. In mid March 1814 it crossed the Rhine and fought in Flanders in order to blockade Antwerp.