On December 31, 1810, Czar Alexander I withdrew Russia from the Continental System, and began trading openly with Britain. Napoleon was outraged, and soon sent his massive Grand Army, comprised of soldiers from all the various nations he dominated, to Poland, ready to force a decisive battle with the czar's army. The Grand Army consisted of over 600,000 troops, and it was a great threat as it waited, menacingly, on Russia's border. Russia, however, did not attack. After playing a waiting game, Napoleon moved his army into Russia in June 1812. Instead of fighting a major battle, the Russians continued retreating, burning and destroying the countryside they left behind. In September, at the Battle of Borodino, the Grand Army finally confronted the Russians, and won a victory. Napoleon then entered Moscow, which had been ruined under the Russian scorched-earth policy. As the French occupied the city, the Russian winter began to take hold unusually early. This winter of 1812 would be brutally harsh. Lacking food and adequate shelter to face the winter, Napoleon tried to negotiate with Alexander, who refused. Napoleon's only choice was to retreat, but the Russian winter decimated the Grand Army. Napoleon emerged from Russia with only a handful of the soldiers he took in.
In December of 1812 Napoleon sensed trouble. He left his shattered army, and hurried back across Europe to Paris. There, he quickly raised a new army, although this one was not trained as well as the veterans of the Grand Army he had lost in Russia.
Napoleon's intuition was correct. In 1813, Austria and Prussia quickly joined Alexander's side, and many German patriots from the Confederation of the Rhine rushed to join this new coalition. Meanwhile, in June 1813, Wellington threatened France from his position in Spain. In October of 1813, Napoleon's new army fought the coalition at Leipzig, also called the "Battle of Nations." Napoleon lost.
After much negotiating and wrangling, on April 4, 1814, Napoleon finally abdicated by the Treaty of Fontainebleau. Talleyrand suggested Louis XVIII, a Bourbon, as the new king of France. This suggestion brooked the least conflict, so it won out. Louis XVIII had the good sense not to try and return France to the way it was before the Revolution. He accepted a "Constitutional Charter", allowed legal equality and equal access of all to government jobs, and he kept the Napoleonic Code and several other reforms.
On May 30, 1814, Louis XVIII signed the Treaty of Paris, which constrained France to its 1792 boundaries. Napoleon was exiled to the isle of Elba.
Although his Continental System was a disastrous failure, by 1811, Napoleon was undoubtedly the dominant force in Europe. But though it looked strong, his Empire was becoming increasingly riddled with weaknesses. French dominance inspired local nationalism in Germany and Spain, and Napoleon's more established enemies bided their time. In Russia, Alexander I had soured on Napoleon since Napoleon had insulted the czar by recreating Poland and calling it The Grand Duchy of Warsaw. Furthermore, the exiled Prussian Baron Stein was now in Alexander's court, whispering against Napoleon in Alexander's ear. The czar needed little encouragement to turn on his former ally.