At the outbreak of World War I he was the nominal supreme commander of the Serbian army; true command was in the hands of the Chief of Staff of Supreme Headquarters, a position held by Stepa Stepanović (during the mobilisation), Radomir Putnik (1914–1915), Petar Bojović (1916–1917) and Živojin Mišić (1918). The Serbian army distinguished itself in the battles at Cer and at the Drina (the Battle of Kolubara) in 1914, scoring victories against the invading Austro-Hungarian forces and evicting them from the country.