Dąbrowski was born to Jan Michał Dąbrowski and Zofia Maria Dąbrowska, née Sophie von Lettow, in Pierzchów, Crown of the Kingdom of Poland, on the 29th of August 1755. He grew up in Hoyerswerda, Electorate of Saxony, where his father served as a Colonel in the Saxon Army.
Jan Dąbrowski served for some years in the Saxon army but when, in 1791, the Polish diet recalled all Poles serving abroad, he returned to his native land. Under Poniatowski, he took part in the campaign of 1792 against the Russians. In 1794 he distinguished himself under Kosciusko in the defence of Warsaw.
For two years thereafter he lived in retirement, declining the offers of high ranks in their armies made to him by Russia and Prussia. He then went to Paris, and in January 1797 was authorized by the government of the Cisalpine Republic to organize a Polish legion. This task he executed at Milan. In command of his legion he played an important part in the war in Italy, entered Rome in May 1798, and distinguished himself greatly at the Trebbia (June 19, 1799), and in other battles and combats of 1799-1801. After the peace of Amiens he passed, as general of division, into the service of the Italian republic.
Summoned by Napoleon in 1806 to promote a rising in Poland, he organized several divisions of Poles, and distinguished himself at Danzig and at Friedland. In 1809 he served in the Polish campaign and in 1812 he commanded a Polish division in the Grande Armée, being wounded at the passage of the Beresina. He fought under Marmont at the battle of Leipzig (1813), and in the following year returned to Poland.
He was one of the generals entrusted by the tsar with the reorganization of the Polish army, and was named in 1815 general of cavalry and senator palatine of the new kingdom of Poland. He retired, however, in the following year, to his estates in Posen. He wrote as well several military historical works in the Polish language.
Dąbrowski was known for his involvement in promoting the cause of Polish independence abroad, participation in Napoleonic Wars, Polish-Austrian war and the French invasion of Russia. He was the founder of the Polish Legions in Italy and he contributed to the brief restoration of the Polish state during the Greater Poland Uprising of 1806.
