He began his military service in 1806 during the Wielkopolska Uprising when he personally funded the formation of the first regiment of Legia Poznanska (Poznań Legion), and took the command of the unit.

[1] In the 1812 War against Russia (which Napoleon referred to as his "Second Polish Campaign") he commanded a cavalry brigade in Count Józef Poniatowski's 5th Corps.

After the death of Poniatowski on 19 October 1813, Sułkowski was briefly the main commander of the Polish Corps, even though he was only twenty eight years old at the time.

However, by 1818 he became disillusioned with the political situation, lack of real autonomy or independence for the quasi-Polish state, and the tsar's refusal to join lands of the Russian partition to Congress Poland.

During the November Uprising against Russia in Congress Poland in 1830, Sułkowski considered joining the insurrection but made a condition of his involvement that he be given his own separate military unit to command.

Unlike his parents, however, the younger Sułkowski became a Polish patriot, supposedly after witnessing the Warsaw Uprising of 1794 against Russian rule as an eight-year-old.