After the French Revolution broke out, Prussia joined the anti-French alliance, but was defeated by the French army. 1795, Prussia was forced to agree to France's annexation of Prussia territory west of the Rhine. His son Friedrich Wilhelm Ⅲ (acceded to the throne in 1797) participated in the anti-French wars in 1806 and 10, and was defeated by Napoleon in Jena and forced to flee to Koenigsberg. 1807, Prussia and France concluded a peace treaty in Tilsit, Nieman River, and Prussia ceded160,000 square kilometers of land, including most of Poland's territory (the second and third partition of Poland, the southern half of Poland's territory for the first time) and all the territory west of the Elbe River, and paid reparations1300,000 francs.