After losing 500,000 soldiers in Russia between June and December 1812, Napoleon started rebuilding his army in early 1813 to stop the Russians in Germany. At the end of 1812, Tsar Alexander I of Russia made the momentous decision to continue his war with Napoleon and drive the French from Central Europe. The destruction of the Grande Armée of 1812 provided Alexander with an opportunity to build a Russian-dominated coalition to liberate Europe. Russian pressure forced the French to fall back from the Vistula (Wisła) River and then across the Oder (Odra) River to Berlin by mid February 1813. Hoping to stop the pursuing Russians before they could step foot onto German soil, Napoleon looked to his ally, King Frederick William III of Prussia, for assistance. As Eugène de Beauharnais, the viceroy of Italy and commander of imperial forces on the eastern front, surrendered land for time, direct negotiations between the Russians and Prussians commenced.

With two-thirds of Prussia occupied by Napoleon’s forces, Frederick William made the bold decision to break the French alliance and join the Russians to form the Sixth Coalition. Negotiations culminated on 28 February 1813 with the signing of the Treaty of Kalisch: the much-anticipated Russo-Prussian military alliance. The Prussians agreed to field an army of 80,000 men to assist a Russian contingent of 150,000; both states pledged not to make a separate peace with Napoleon. The British did their part to bolster the new coalition by promptly dispatching arms and ammunition to the Baltic for use by the Russians and Prussians. Alexander also hoped for an Austrian alliance in early 1813 but Austria’s foreign minister, the adroit Klemens von Metternich, feared Russian success would be accompanied by Russian territorial expansion. With Alexander’s armies approaching Central Europe, the Austrians declared neutrality.