On 25 June 1807, in Tilsit, Napoleon and Alexander embraced each other on a raft anchored to the center of the river Niemen. Two weeks later imperial France and imperial Russia signed a peace treaty and alliance in what has been called « dividing up the world between them ». The truth is that Tilsit was diplomatic play-acting, on both sides. On the one hand, Napoleon as victor was attempting to shore up French preponderance in Europe, leaving to his new ally merely dominance and surveillance in the East. On the other hand, the Emperor of Russia, beaten at Friedland after three years of war, wanted to reconstitute his forces before beginning again his traditional diplomacy ‑ inherited from Peter the Great and Catherine II ‑ of advancing towards the West, the South and the North. French and Russian interests were too diametrically opposed at the beginning of the 19th century for peace to have the tiniest chance of resisting the deep forces of geopolitics. War therefore began again five years later and ended, in the final analysis, with a triumph for Alexander relatively speaking.