Treaties of Tilsit in the context of Fall of Berlin (1806)

The Napoleonic Wars (1803–1815) were a global series of conflicts fought by a fluctuating array of European coalitions against the French First Republic (1803–1804) under the First Consul followed by the First French Empire (1804–1815) under the Emperor of the French, Napoleon Bonaparte. The wars originated in political forces arising from the French Revolution (1789–1799) and from the French Revolutionary Wars (1792–1802) and produced a period of French domination over Continental Europe. The wars are categorised as seven conflicts, five named after the coalitions that fought Napoleon, plus two named for their respective theatres: the War of the Third Coalition, War of the Fourth Coalition, War of the Fifth Coalition, War of the Sixth Coalition, War of the Seventh Coalition, the Peninsular War, and the French invasion of Russia.

The first stage of the war broke out when Britain declared war on France on 18 May 1803. After some minor campaigns, Britain allied with Austria, Russia, and several minor powers to form the Third Coalition in April 1805. Napoleon defeated the allied Russo-Austrian armies in the subsequent war which climaxed in French victories at Ulm and at Austerlitz, leading to the dissolution of the Holy Roman Empire and Austria being forced to make peace by the end of the year. Britain and Russia remained at war with France. Concerned about increasing French power, Prussia joined Britain and Russia in the Fourth Coalition, which resumed war in October 1806. Napoleon defeated the Prussians at Jena-Auerstedt and the Russians at Friedland, bringing an uneasy peace to the continent by July 1807, and again leaving Britain as France's sole major enemy. Britain was unable to dispute French dominance on the continent but obtained hegemony over the seas after a string of victories including Trafalgar. Russia used the interim peace to resolve wars with the Ottomans, Swedes, and Iranians.

The Duchy of Warsaw (Polish: Księstwo Warszawskie; French: Duché de Varsovie; German: Herzogtum Warschau), also known as the Grand Duchy of Warsaw and Napoleonic Poland, was a French client state established by Napoleon Bonaparte in 1807, during the Napoleonic Wars. It initially comprised the ethnically Polish lands ceded to France by Prussia under the terms of the Treaties of Tilsit, and was augmented in 1809 with territory ceded by Austria in the Treaty of Schönbrunn. It was the first attempt to re-establish Poland as a sovereign state after the 18th-century partitions and covered the central and southeastern parts of present-day Poland.

The duchy was held in personal union by Napoleon's ally, Frederick Augustus I of Saxony, who became the duke of Warsaw and remained a legitimate candidate for the Polish throne. Following Napoleon's failed invasion of Russia, Napoleon seemingly abandoned the duchy, and it was left to be occupied by Prussian and Russian troops until 1815, when it was formally divided between the two countries at the Congress of Vienna. The east-central territory of the duchy acquired by the Russian Empire was subsequently transformed into a polity called Congress Poland, and Prussia formed the Grand Duchy of Posen in the west. The city of Kraków, Poland's cultural centre, was granted "free city" status until its incorporation into Austria in 1846.

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The Electorate of Hesse (German: Kurfürstentum Hessen), also known as Hesse-Kassel or Kurhessen, was the title used for the former Landgraviate of Hesse-Kassel after an 1803 reform where the Holy Roman Emperor elevated its ruler to the rank of Elector, thus giving him a vote in any future elections to the emperorship. When the Holy Roman Empire was abolished in 1806, William I, Elector of Hesse, chose to retain the title of Elector, even though there was no longer an Emperor to elect. In 1807, with the Treaties of Tilsit, the area was annexed to the Kingdom of Westphalia, but in 1814, the Congress of Vienna restored the electorate.

The Prussian Reform Movement was a series of constitutional, administrative, social, and economic reforms early in 19th-century Prussia. They are sometimes known as the Stein–Hardenberg Reforms, for Karl Freiherr vom Stein and Karl August von Hardenberg, their main initiators. German historians, such as Heinrich von Treitschke, saw the reforms as the first steps towards the unification of Germany and the foundation of the German Empire before the First World War.

The reforms were a reaction to the defeat of the Prussians by Napoleon I at the battle of Jena-Auerstedt in 1806, leading to the second Treaty of Tilsit, in which Prussia lost about half its territory and was forced to make massive tribute payments to the First French Empire. To make those payments, it needed to rationalize its administration.