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Invasion of Russia

Tsar Alexander saw the creation of the Grand Duchy of Warsaw, Napoleon's marriage alliance with Austria and the election of the French Marshal Bernadotte as Crown Prince of Sweden as attempts to contain Russia. In December 1810, Napoleon annexed the Duchy of Oldenburg which Alexander considered an insult as his uncle was the duke. The Tsar responded by allowing neutral shipping into Russian ports and banning most French imports. Russia feared that Napoleon intended to restore the Kingdom of Poland while Napoleon suspected Russia of seeking an alliance with Britain against France.

In late 1811, Napoleon began planning an invasion of Russia. A Franco-Prussian alliance signed in February 1812 forced Prussia to provide 20,000 troops for the invasion and, in March, Austria agreed to provide 30,000 men. Napoleon's multinational grande armée comprised around 450,000 frontline troops of which about a third were native French speakers. Napoleon called the invasion the "Second Polish War," but he refused to guarantee an independent Poland for fear of alienating his Austrian and Prussian allies.

On 24 June, Napoleon's troops began crossing the Nieman river into Russian Lithuania with the aim of luring the Russians into one or two decisive battles. The Russians retreated 320 kilometres east to the Dvina river and implemented a scorched earth policy, making it increasingly difficult for the French to forage food for themselves and their horses. On 18 August, Napoleon captured Smolensk with the loss of 9,000 of his men, but the Russians were able to withdraw in good order.

The Russians, now commanded by Kutuzov, made a stand at Borodino, outside Moscow, on 7 September. The battle resulted in 44,000 Russian and 35,000 French dead, wounded or captured, in one of the bloodiest days of battle in Europe up to that time. The Russians withdrew overnight and Napoleon later stated, "The most terrible of all my battles was the one before Moscow. The French showed themselves worthy of victory, and the Russians worthy of being invincible".

The Russians retreated to Tarutino, and Napoleon entered Moscow on 14 September. The following evening, the city was set on fire on the orders of its governor Feodor Rostopchin. Alexander, in St Petersburg, refused to negotiate a peace, and after six weeks Napoleon's army evacuated Moscow.

After capturing Maloyaroslavets with the loss of 4,000 to 10,000 men, Napoleon retreated towards Smolensk. The French were attacked by Cossacks and peasants and suffered from the intense cold, disease and lack of food and water. Around 40,000 to 50,000 troops reached Smolensk on 9 November, a loss of about 60,000 in three weeks. Napoleon also heard that an attempted coup by General Malet in Paris had only narrowly failed.

From Smolensk, Napoleon's army headed for Vilnius, where there was a French garrison of 20,000. In late November, under attack from all sides by Russian forces, the grande armée managed to cross the Berezina river on pontoon bridges in temperatures reaching −40 °C (−40 °F). On 5 December, shortly before arriving in Vilnius, Napoleon left his disintegrating army for Paris. In the following weeks, the remnants of the grande armée, about 75,000 troops, crossed the Nieman into allied territory. Russian military losses in the campaign were up to 300,000 and total deaths were up to one million.