In 1807, the Duchy of Warsaw was established in the recaptured territories, essentially as a satellite of Bonaparte's France. Dąbrowski became disappointed with Napoleon, who offered him monetary rewards, but no serious military or government position. He was also awarded the Virtuti Militari medal that year. In 1809, he set out to defend Poland against an Austrian invasion under the command of Prince Józef Poniatowski. Joining the Army of the Duchy of Warsaw shortly after the Battle of Raszyn, he took part in the first stages of the offensive on Galicia, and then organized the defense of Greater Poland. In June 1812, Dąbrowski commanded the 17th (Polish) Infantry Division in the V Corps of the Grande Armée, during Napoleon's invasion of Russia. However, by October the Franco-Russian war was over and the French forces, decimated by a severe winter, had to retreat. At the disastrous Battle of Berezina in late November that year, Dąbrowski was wounded, and his leadership and tactics in it were criticized. After the March reorganization of the Grande Armée, he commanded the 27th (Polish) Infantry Division in the VIII Corps. He commanded it at the Battle of Leipzig (1813), and subsequently on 28 October he became the commander in chief of the all remaining Polish forces in Napoleon's service, succeeding Antoni Paweł Sułkowski.