The upheaval of 1918 saw Celje in a situation of heightened national antagonism, and the sharp division between Germans and Slovenes also affected the state of education. On 1 November 1918, the national government of the State of Slovenians, Croats and Serbs declared Slovenian the official language within its territory, and in the same month it introduced Slovenian as the language of instruction in primary and secondary schools. For members of other nations, the decree provided for minority schools with the national language as a compulsory subject, provided there were sufficient school-age children. In January 1919, the Slovenian school authorities began more actively to dismiss German-oriented teachers and to appoint Slovene ones. Former German schools were converted into Slovenian schools and German parallel schools were set up for German pupils. After the 1918 upheaval, school celebrations were changed and new subjects were introduced (Serbo-Croatian, history of the Karađorđević dynasty).