Treaty of Kalisz (1813)

The Treaty of Kalisz was signed in Kalisz (Kalisch, Kalish/Калиш) on 28 February 1813, between Russia and Prussia against Napoleon I. It marked the final changeover of Prussia onto the side against Napoleon.

The events that led to this alliance date back to 30 December 1812, at Tauroggen when Lieutenant-General Ludwig Yorck von Wartenburg, on behalf of his Prussian troops, and General Hans Karl von Diebitsch of the Russian Army signed the Convention of Tauroggen. The Convention of Tauroggen armistice, signed by Diebitsch and Yorck, "neutralised" the Prussian corps without consent of their king. The news was received with the wildest enthusiasm in Prussia, but the Prussian Court dared not yet throw off the mask, and an order was dispatched suspending Yorck from his command pending a court-martial. Two months later, the Prussians officially switched sides when both Prussia and Russia agreed to establish an alliance known as the Kalisz Union against Napoleon I.

The treaty is also an interesting example of the dominance of the French language at this time. The text of the treaty was written in French, even though it was positioned to defeat France.