In 1804 the Serbian Revolution erupted. It began as an uprise against the abuse of power by the janissaries. At that time, the Serbs had the Ottoman Empire on their side, but a clash soon occurred, and the Serbs demanded their independence. The Serbs, guided by their powerful leader Karageorgi Petrovic, were victorious against the Ottomans but were ultimately defeated when Russia abandoned them. In 1815, Milos Obrenovic took over Karageorgi's struggle. Under Obrenovic's guidance, the Serbs were gradually gaining more extensive autonomy. Serbia became independent in 1878. During their struggle, the Serbs had assistance and support from Greek fighters who run alongside them on the battlefields.