The French invasion of Russia in 1812 was a pivotal moment in the Napoleonic Wars. It destroyed Napoleon’s half a million-strong Grande Armée and severely undermined his reputation as a military commander. The invasion began on 24 June 1812 as Napoleon sought to compel Alexander I to maintain Russia’s role in the Continental System, an alliance of nations against British trade. The French enjoyed an early victory at the Battle of Smolensk in mid-August but were prevented from marching on St Petersburg following the Battle of Polotsk. Consequently, the Grande Armée marched on Moscow as the Russians retreated. A major land battle, the bloodiest of the Napoleonic Wars, took place as the two armies met at the Battle of Borodino near Moscow on 7 September (Tchaikovsky’s 1812 Overture was composed to commemorate the defence of Moscow at the Battle of Borodino). Although the French eventually won the battle, it proved to be a Pyrrhic victory. Napoleon entered Moscow on 14 September after the Russians had evacuated the city. The Russians, however, refused to capitulate. On 19 October Napoleon began the disastrous retreat from Moscow as the Russian winter approached. By November the Grande Armée had been reduced to fewer than 30,000 fit soldiers: more than 450,000 men had been killed or captured. Napoleon’s Russian campaign ended on 14 December 1812 as the last troops left the country; Napoleon, however, had returned to Paris to try to secure his position as emperor. The Russian campaign severely weakened France’s position in Europe and, in many ways, led to Napoleon’s subsequent downfall.