The renegade janissaries, known as dahia, took control of the Smederevan Sanjak in 1802, after murdering Vizier Hadži Mustafa Pasha.

The four leaders divided the Sanjak, ruling as dictators, also removing the rights granted by Sultan Selim III.

Sima finished Velika škola Ivana Jugovića -- the Grandes écoles-- in Belgrade, and military school in Vienna.

Sima's uncle, Jakov Nenadović, was one of the most distinguished revolutionary commanders, and the first Serbian Minister of Interior (1811–1813).

With the suppression of the revolt by the Ottomans, Sima fled Serbia and helped his brother Mateja in his diplomatic missions (1814–15).