I had written an entire epilogue to the Napoleonic Wars, however apparently I didn't save it so, I'll give a brief synopsis.
In May 1809, Napoleon decided to proceed with his invasion of Russia and Byzantium. Dividing his Grand Armée into two groups, he would lead a larger army through Poland and to capture Moscow. The second army would go southwards and capture Constantinople. In Hungary organized resistance was initially weak, and he soon carved out puppet states out of Croatia, Illyria (Albania) and Transylvania. However, soon armed bands of Greeks, Serbs and Bulgarians began attacking French positions. Also, Hungarian and Polish nobles formed small armies that would harass the French and wear down their morale.
After capturing Warsaw, his army is defeated at Mogilev in September 1809. This forces him to retreat south to Kiev where he winters. However, a large Austro-Prussian Army defeats the French outside of Vienna, and marches eastward towards Hungary. Napoleon's forces are cutoff from reinforcements and badly in need of provisions. Therefore, he changes his mind to head southward along the Black Sea.
Throughout 1810-1811 Napoleon is able to still achieve some impressive victories despite meagre resources. However, he is bogged down fighting ever large numbers of allied armies. Once he hears of the invasion of France, he makes an attempt to quickly return his army to France where he can regroup.
However, by 1810, the French Imperial Army has been pushed out of Iberia and is fighting in the Pyrenees. Here the French Imperial Army manages to hold off the combined British & British American, Spanish, French Royalist and Aragonese Army until 1811. However, in 1810 more troops were brought from North America and Britain to Barcelona. By mid-1811 they have managed to capture much of southern France where Royalist sympathies are high.
In Italy, the British Aid the Savoyards in assembling an invasion force. By September 1810, a rebellion in Italy against the French breaks out. The rebels call for an Italian Republic, it begins in Florence, and spreads to Bologna and Rome. In October, the Savoyard forces land a small army at Civitavecchia and take Rome by December. Soon an Italian Army of 100,000 men is assembled under King Victor Emanuel I. This causes large numbers of Italians to defect from Napoleon's troops. By spring of 1811 they have invaded the Swiss Confederation.
This leads the Bourbons in Sicily to assemble an invasion force and in May 1811, they invade Calabria, and capture Naples in October, driving Napoleon's brother from the throne there.
In Germany meanwhile, the Swedes and Danes along with the Prussians have control of the Baltic Coast and the Prussians liberate the Netherlands in May 1811. This is followed by a British/French Royalist invasion at Dunkirk in July. In the meantime, the German states begin rebelling against French rule, with more and more men joining the anti-Napoleonic Coalition.
Also in May 1811, a pro-royalist rebellion begins in Western France. This is initially quelled, but French Imperial troops in France are stretched thin. Hearing of the events in France, in October 1811 Napoleon hopes to return to France. However, at Valmy the French Imperial troops are defeated by a much larger force. This leads to a collapse of the French government and a French Royalist Army triumphantly enters Paris, hoisting the Fleur-de-Lys over the Tuileries Palace for the first time in twenty years.
Napoleon meanwhile fights on, however he is defeated after an exhausting four-day battle at Sarajevo in November 1811. His men soon get word of events in Paris, and they begin to surrender to the Austro-Russian army. In the end, the general had hoped he could achieve a stunning victory, but by that time all of Europe was against him, and his forces were outnumbered 5 to 1 on the battlefield. Napoleon formally signs his surrender and abdication, ending twenty-years of war in Europe.