In 1805 he took the nom de guerre of Božidar Grujović before leaving his post as a university professor to go to Karađorđe's Serbia to fight the Turks.
Education was fostered, and an enlightened parliament began to prepare a new constitution that should rid the obstructive Turkish ways.
It addressed the many unresolved questions plaguing Serbia and its people (who had enough of Turkish rule), such as issues concerning liberty, property, and human dignity.
Filipović was part of a group of Serbian economic thinkers (such as Dositej Obradović, Zaharije Orfelin, Jovan Muškatirović, Ivan Jugović, Pavle Solarić, Emanuilo Janković, Atanasije Stojković, Vićentije Rakić and others) who supported the cameralist principles of rational economic conduct and the development of new sciences and methodologies.
G. Vukadinović, Shvatanje prirodnog prava Božidara Grujovića [B. Grujović's Notion of Natural Law] in Pola veka nauke i tehnike u obnovljenoj Srbiji 1804–1854 (Kragujevac, 1996), pages 79–83.