from what i found...
Napoleon's Russian Campaign of 1812 was one of the greatest disasters in military history. Napoleon invaded Russia at the head of an army of over 600,000 men but by the start of 1813 only 93,000 of them were still alive and with the army. The Russians had prevented Napoleon from fighting the decisive battle he wanted until he was at the gates of Moscow, and their refusal to negotiate after he captured the city eventually forced the French to carry out a lengthy and very costly retreat, harassed by the cold and by Cossacks. The retreat from Moscow was one of the defining images of the Napoleonic period, and the disaster in Russia helped convince many of Napoleon's former allies to turn against him, especially in Germany. Within two years Napoleon went from the master of most of Europe to abdication and his first exile.