After an eight-day offensive that marked the beginning of a new, aggressive strategy in the region, Austro-Hungarian troops under commander in chief Franz Conrad von Hotzendorf take control of the Balkan state of Montenegro, which surrendered on January 25.
By the end of 1915, after initial setbacks, the Central Powers had completed their conquest of Serbia, the upstart Balkan country that they claimed had provoked the war in June 1914, when a Serbian nationalist had assassinated Austrian Archduke Franz Ferdinand. Despite their success in the Balkans, Conrad was incensed that the victories had been achieved largely by German, not Austrian, forces.