The Day Napoleon Lost Everything An invincible emperor, faced with his first major defeat. Why did his expedition turn into a human catastrophe? Napoleon launched his invasion of Russia in June 1812 to force the Tsar to uphold the Continental Blockade against England. But his massive army, initially about 600,000 soldiers strong, lost half its numbers within weeks due to long marches, dwindling supplies, disease, and weakened discipline. Kutuzov and Barclay de Tolly adopted a strategy of attriti