The 1807 treaty between Napoleon and Alexander I that appears in War and Peace’s historical background was the Treaty of Tilsit.
More precisely, the Treaties of Tilsit were a pair of agreements signed in July 1807 after Napoleon’s victory over the Fourth Coalition. The first, signed on July 7, ended hostilities between France and Russia. Napoleon and Alexander famously met on a raft in the Neman River near Tilsit, a theatrical gesture presenting the two emperors as equals.
The settlement temporarily transformed European diplomacy. France and Russia agreed to cooperate, while Russia accepted participation in Napoleon’s Continental System against Britain. A second treaty, signed on July 9, imposed severe territorial losses on Prussia and helped Napoleon reorganize central Europe through client states such as the Duchy of Warsaw.
A common mix-up is with Schönbrunn, the 1809 treaty between France and Austria, or Amiens, the 1802 peace agreement between Britain and France. Tilsit is especially important to War and Peace because Tolstoy’s story begins amid the Napoleonic conflicts that reshaped Russia and Europe. The alliance soon deteriorated, leading to Napoleon’s invasion of Russia in 1812.