Treaties of Tilsit, (July 7 [June 25, Old Style] and July 9 [June 27], 1807), agreements that France signed with Russia and with Prussia (respectively) at Tilsit, northern Prussia (now Sovetsk, Russia), after Napoleon’s victories over the Prussians at Jena and at Auerstädt and over the Russians at Friedland.
Under the terms of the treaty, France and Russia became allies and divided Europe between them, reducing Austria and Prussia to helplessness. Alexander I of Russia accepted the reduction of Prussia from 89,120 to 46,032 square miles (230,820 to 119,223 square km); the creation from the Polish provinces detached from Prussia of a new Grand Duchy of Warsaw for Napoleon’s ally, the king of Saxony; and the establishment of the Kingdom of Westphalia in northern Germany. Westphalia, too, was in part composed of former Prussian lands. Napoleon’s hegemony in western and central Europe was thus established. Prussia was to be occupied by French troops until a war indemnity, fixed at 120,000,000 francs, had been paid.
In secret provisions Napoleon agreed to help Russia “liberate” most of European Turkey if Turkey rejected French mediation in its conflict with Russia. Similarly, Alexander promised to join the Continental System against British trade if Britain rejected Russian mediation in its conflict with France. Russia was given a free hand to conquer Finland from Sweden. Prussia was forced to join the Continental System and close its ports to British trade.
Because the Treaties of Tilsit came so close to creating a continental blockade that excluded British trade, Napoleon sought in the next few years to enlarge and enforce the blockade. This led to the collapse of the peace on the continent. The period of Franco-Russian collaboration lasted until Dec. 31, 1810, when the tsar, finding that the alliance to the Continental System seriously hurt Russian trade, opened Russian ports to neutral ships. The threat to Russia from Napoleon’s satellite, the Grand Duchy of Warsaw, on Russia’s border, also contributed to the eventual failure of the Franco-Russian alliance. Napoleon invaded Russia in June 1812.