When was the annexation of Bosnia finally approved by Serbia ?
The Bosnian Crisis of 1908–1909 ( also referred to as the " Annexation crisis " ) erupted into public view when on October 5 , 1908 , Bulgaria declared its independence and on October 6 , 1908 , Austria - Hungary announced the annexation of Bosnia and Herzegovina , which was populated mainly by south Slavic nationals ( Serbs , Croats and Bosniaks ) .