On 14 June Napoleon obtained an overwhelming victory over the Russians at the Battle of Friedland, wiping out the majority of the Russian army in a very bloody struggle. The scale of their defeat convinced the Russians to make peace with the French.
On 19 June, Tsar Alexander sent an envoy to seek an armistice with Napoleon. The latter assured the envoy that the Vistula River represented the natural borders between French and Russian influence in Europe. On that basis, the two emperors began peace negotiations at the town of Tilsit after meeting on an iconic raft on the River Niemen. The very first thing Alexander said to Napoleon was probably well-calibrated: "I hate the English as much as you do".
Moreover, Alexander's pretensions at friendship with Napoleon led the latter to seriously misjudge the true intentions of his Russian counterpart, who would violate numerous provisions of the treaty in the next few years. Despite these problems, the Treaties of Tilsit at last gave Napoleon a respite from war and allowed him to return to France, which he had not seen in over 300 days.