The formal independence of the country was internationally recognised at the Congress of Berlin in 1878, which ended the Russo-Turkish War; this treaty, however, prohibited Serbia from uniting with other Serbian regions by placing Bosnia and Herzegovina under Austro-Hungarian occupation, alongside the occupation of the region of Raška. From 1815 to 1903, the Principality of Serbia was ruled by the House of Obrenović, save for the rule of Prince Aleksandar Karađorđević between 1842 and 1858. In 1882, Principality of Serbia became the Kingdom of Serbia, ruled by King Milan I. The House of Karađorđević, descendants of the revolutionary leader Karađorđe Petrović, assumed power in 1903 following the May Overthrow.