Battle of Leipzig - Wikipedia

On October 16, 1813, the Battle of Leipzig occurred. It was the largest battle in Europe prior to WWI. Napoleon's forces were defeated by Prussia, Austria and Russia. From the article:

"The Battle of Leipzig or Battle of the Nations (Russian: Битва народов, Bitva narodov; German: Völkerschlacht bei Leipzig; French: Bataille des Nations, Swedish: Slaget vid Leipzig) was fought from 16 to 19 October 1813, at Leipzig, Saxony. The coalition armies of Russia, Prussia, Austria, and Sweden, led by Tsar Alexander I of Russia and Karl Philipp, Prince of Schwarzenberg, decisively defeated the French army of Napoleon I, Emperor of the French. Napoleon's army also contained Polish and Italian troops, as well as Germans from the Confederation of the Rhine. The battle was the culmination of the 1813 German campaign and involved 600,000 soldiers, 2,200 artillery pieces and the expenditure of 200,000 rounds of artillery ammunition, making it the largest battle in Europe prior to World War I.

Decisively defeated for the first time in battle, Napoleon was compelled to return to France while the Coalition kept up their momentum, dissolving the Confederation of the Rhine and invading France early the next year. Napoleon was forced to abdicate and was exiled to Elba in May 1814.

The French Emperor Napoleon I attempted to militarily coerce Tsar Alexander I of Russia into rejoining his unpopular Continental System by invading Russia with about 650,000 troops, collectively known as the Grande Armée, and eventually occupied Moscow in late 1812, after the bloody yet indecisive Battle of Borodino. However, the Russian Tsar refused to surrender even as the French occupied the city, which was burnt by the time of its occupation.[5] The campaign ended in complete disaster as Napoleon and his remaining forces retreated during the bitterly cold Russian winter, with sickness, starvation, and the constant harrying of Russian Cossack marauders and partisan forces leaving the Grande Armée virtually destroyed by the time it exited Russian territory. Making matters even worse for Napoleon, in June 1813 the combined armies of Great Britain, Portugal, and Spain, under the command of Britain's Arthur Wellesley, Marquess of Wellington, had decisively routed French forces at the Battle of Vitoria in the Peninsular War, and were now advancing towards the Pyrenees and the Franco-Spanish border. With this string of defeats, the armies of France were in retreat on all fronts across Europe.

Anti-French forces joined Russia as its troops pursued the remnants of the virtually destroyed Grande Armée across central Europe. The allies regrouped as the Sixth Coalition, comprising Russia, Austria, Prussia, Sweden, Great Britain, Spain, Portugal, and certain smaller German states whose citizens and leaders were no longer loyal to the French emperor.[6] Napoleon hurried back to France and managed to mobilize an army about the size of the one he had lost in Russia, but severe economic hardship and news of battlefield reverses had led to war-weariness and growing unrest among France's citizenry.[7]

Despite opposition at home, Napoleon rebuilt his army, with the intention of either inducing a temporary alliance or at least cessation of hostilities, or knocking at least one of the Great Powers of the Coalition out of the war. He sought to regain the offensive by re-establishing his hold in Germany, winning two hard-fought tactical victories, at Lützen on 2 May and Bautzen on 20–21 May, over Russo-Prussian forces. The victories led to a brief armistice. He then won a major victory at the Battle of Dresden on 27 August. Following this, the Coalition forces, under individual command of Gebhard von Blücher, Crown Prince Charles John of Sweden, Karl von Schwarzenberg, and Count Benningsen of Russia, followed the strategy outlined in the Trachenberg Plan: they would avoid clashes with Napoleon, but seek confrontations with his marshals. This policy led to victories at Großbeeren, Kulm, Katzbach, and Dennewitz. After these defeats, the French emperor could not easily follow up on his victory at Dresden. Thinly-stretched supply lines spanning now somewhat hostile Rhineland German lands, coupled with Bavaria's switching of sides to the Coalition just eight days prior to the battle, made it almost impossible to replace his army's losses. As a result, by the time of the battle, the total strength of all Coalition armies east of the Rhine probably exceeded a million; by contrast Napoleon's forces had shrunk to just a few hundred thousand."