World War I started in the Balkans where Hungary and Russia congregated for control. Austria conquered the Ottoman Provinces of Bosnia and Herzegovina, which angered Russia and its ally Serbia. Austria-Hungary blamed Serbia for assassinating the Archduke Franz Ferdinand. This was what caused the European Alliances to push all of the powers into war. (Henretta, 642) Russia was linked to Serbia by a secret treaty and they assembled their armies against Austria-Hungry.