of the slain Serbs mounted on a tower to serve as a warning. The structure became known as Skull Tower (). In 1821, the Ottomans arrested the Bishop of Niš, Milentija, as well as 200 Serbian patriots, on charges of preparing an uprising in the Niš area in support of the Greek War of Independence. On June 13 of that year, Bishop Milentija and other Serbian leaders were hanged in public. In the 19th century Niš was an important town, but populated by Bulgarians in the 19th century, when the Niš rebellion broke out in 1841. According to Ottoman statistics during the Tanzimat the population of Sanjak of Niš was treated as Bulgarian, and according to French travelers such as Jérôme-Adolphe Blanqui and Ami Boue in 1837/1841. According to all authors between 1840-72 the delineation between Bulgarians and Serbs is undisputed and ran north of Nis, although one author Cyprien Robert claims that half of the population of the town was made up by Serbians. Serbian cartographers of the time (such as Dimitrije Davidović in 1828 and Milan Savić in 1878) also accepted South Morava river as such delineation and added Niš outside the borders of the Serbian people. The urban population of Niš consisted of 17,107 Christian and 4,291 Muslim males, with total number of 3,500 Serbian houses and 2,000 Muslim houses. Muslim population of Niš consisted mainly of Turks, of which a part were of Albanian origin, and the rest were Muslim Albanians and Muslim Romani. In 1870, Niš was included in the Bulgarian Exarchate. Before the area had been under the Ecumenical Patriarchate of Constantinople and the Serbian Patriarchate of Peć. The city was also stipulated the area to be ceded to Bulgaria according to the Constantinople Conference in 1876. Niš was finally liberated during the Serbo–Ottoman War of 1876–1878. The battle for the liberation of Niš started on December 29, 1877, and the Serbian Army entered Niš on January 11, 1878, and it became a part of Serbia. The Albanian quarter was burned and some of the town's Muslim population fled to the Ottoman vilayet of Kosovo, resettling in Pristina, while others went to Skopje. The number of remaining Muslims counted were 1,168, with many being Muslim Romani, out of the pre-war ca. 8,500. The demographics of Niš underwent change whereby Serbs who formed half the urban population prior to 1878 became 80 percent in 1884.