On July 9, 1807, Napoleon officially established the Duchy of Warsaw and the Free City of Danzig at the Treaty of Tilsit.
Following an expeditious campaign that culminated at the Battle of Jena, French forces under Napoleon occupied Prussia and captured Berlin in October 1806. They then advanced all the way through Poland to the Russian frontier, eventually crushing Russian forces at the Battle of Friedland, forcing Russia to sue for peace.
The ensuing Treaties of Tilsit were particularly harsh on Prussia, as Napoleon demanded much of the Prussian territory along the lower Rhine and in what was part of the former Polish–Lithuanian Commonwealth.
Cementing his control over Central Europe, Napoleon created sister republics out of the new acquisitions, which included the Duchy of Warsaw, ruled by his new ally the king of Saxony, and the Free City of Danzig, a semi-independent city-state effectively governed by French general Jean Rapp.
Arguably influenced by Napoleon’s Polish mistress Maria Walewska, the creation of the Duchy of Warsaw gave every appearance of resurrecting the Polish nation from the political grave to which it had been consigned since 1795 by the Partitions of Poland between the Habsburg Monarchy, Prussia and the Russian Empire at the end of the 18th century.
Poles expected that the Duchy would be upgraded to the status of a Kingdom and that after Napoleon’s invasion of Russia, they would be joined by the liberated territories of the Grand Duchy of Lithuania, thereby restoring the former Polish–Lithuanian Commonwealth.
Polish citizens accommodated Napoleon’s Grande Armée and paid large tributes in the preparation of the invasion of Russia, during which they formed by far the largest foreign contingent. Napoleon even termed the war the Second Polish War.
But after Napoleon’s failed invasion of Russia in 1812, the Duchy of Warsaw and the city of Danzig fell to Russian forces and remained occupied by Prussian and Russian troops until 1815, when they were formally partitioned between the two countries at the Congress of Vienna.
Poland would not regain full independence until the end of World War I, when the signing of the Treaty of Versailles and the collapse of the Russian Empire allowed for the resurrection of Polish national sovereignty… and the birth of the Republic of Poland.
The Polish folk song “Dąbrowski’s Mazurka”, originally written to boost the morale of Polish soldiers serving in the Napoleon’s Polish Legions, was officially adopted as the national anthem of Poland in 1926.
Find out more about Central European history in our new On this Day series.