After service in the Saxon Army (1772–92), Dąbrowski joined the Poles to serve against the Russians in 1792. In 1794 he took part in Kościuszko's uprising, distinguished himself in the defense of Warsaw, and then led a separate raid against the Prussians in the province of Poznań. After the Third Partition of Poland (1795) he went to Paris and obtained from the Directory (1796) permission to form a Polish legion in Italy. In command of that legion he played an important part in the war in Italy (1797–1801), entering Rome on May 3, 1798, and distinguishing himself at the Trebbia (June 17–19, 1799), where his legions suffered major losses against the Russians. After the Treaty of Amiens (1802), he passed, as general of division, into the service of the Italian Republic until he was summoned by Napoleon in 1806 to promote a rising in Poland. Arriving in Poznań on November 6, he had, by the end of 1806, organized seven Polish units, which he led in defense of the Napoleonic Duchy of Warsaw, distinguishing himself in the Battles of Danzig (Gdańsk) and Friedland in 1807. In 1809 he served in the Polish campaign against Austria in Galicia, and in 1812 he commanded one of the Polish divisions in the invasion of Russia, where he was wounded while covering the passage of the Berezina River. He fought in the Battle of Leipzig in 1813, and in 1814 he returned to Poland, where he was one of the generals entrusted by the Russian tsar with the reorganization of the Polish Army. In 1815 he was appointed general of cavalry and senator of the new Kingdom of Poland. His military exploits are mentioned in the Polish national anthem, which is also known as the "Dąbrowski Mazurka."