The Russians defeated Napoleon's Grand Army through a combination of well-timed assaults, creating food shortages and holding out until winter came. Most of Napoleon's army was wiped out only about 6 months after it arrived in Russia.
In 1812, Napoleon amassed an army of 400,000-650,000 troops and sent them across the Niemen River. He believed that through sheer numbers he could quickly force Russia to negotiate. In their first move, Russia withdrew from Vilna, which drew the Grand Army further into Russia.
Russia withdrew from Vitebsk and Smolensk soon after, torching both cities as they went. Napoleon's troops found little food. Peasants burned their fields rather than let their food fall into French hands. Napoleon still pushed on.
After a fierce battle at Borodino on September 7, 1812,, the Russians again retreated, this time on the road to Moscow. Napoleon pushed to Moscow despite heavy losses and a short supply of food. The Grand Army arrived in Moscow to discover that it, too, had been set ablaze and most of the food was gone.
Replenished, the Russian Army attacked and Napoleon was forced to retreat on that same road. An early winter resulted in massive casualties of French soldiers and horses, and Napoleon abandoned his army to go to Paris. Nine days afterward, what was left of the Grand Army, now numbering less than 100,000 troops, crossed out of Russia.