In 1793 and 1796 Sultan Selim III proclaimed firmans which gave more rights to Serbs . Among other things , taxes were to be collected by the '' obor-knez '' ( dukes ) ; freedom of trade and religion were granted and there was peace . Selim III also decreed that some unpopular janissaries were to leave the Belgrade Pashaluk as he saw them as a threat to the central authority of Hadži Mustafa Pasha . Many of those janissaries were employed by or found refuge with Osman Pazvantoğlu , a renegade opponent of Sultan Selim III in the Sanjak of Vidin . Fearing the dissolution of the Janissary command in Sanjak of Smederevo , Osman Pazvantoğlu launched a series of raids against Serbians without the permission of Sultan Selim III , causing much volatility and fear in the region . Pazvantoğlu was defeated in 1793 by the Serbs at the Battle of Kolari . In the summer of 1797 the sultan appointed Mustafa Pasha on position of beglerbeg of Rumelia Eyalet and he left Serbia for Plovdiv to fight against the Vidin rebels of Pazvantoğlu . During the absence of Mustafa Pasha , the forces of Pazvantoğlu captured Požarevac and besieged the Belgrade fortress . At the end of November 1797 obor-knezes Aleksa Nenadović , Ilija Birčanin and Nikola Grbović from Valjevo brought their forces to Belgrade and forced the besieging janissary forces to retreat to Smederevo . By 1799 the janissary corps had returned , as they were pardoned by Sultan 's decree , and they immediately suspended the Serbian autonomy and drastically increased taxes , enforcing martial law in Serbia . On 15 December 1801 Hadži Mustafa Pasha , the Vizier of Belgrade Pashaluk was killed by Kuchuk Alija , one of four dahiyas ( renegade jannissary leaders ) . This resulted in the Sanjak of Smederevo being ruled by these renegade janissaries independently from the Ottoman government . Several district chiefs were murdered in the Slaughter of the Knezes on February 4 , 1804 , by the renegade janissaries . This sparked the First Serbian Uprising ( 1804 – 13 ) , the first phase of the Serbian Revolution . The title continued its use by the Serbian revolutionary government . The '' knežina '' ( кнежина ) has a modern equivalent of municipality , as the sizes of the knežine were close to modern municipalities
Slaughter of the Knezes
Slaughter of the Knezes
Obor-knez