Bulgaria decided to join the Central Powers after she was promised by Germany the territory along the Aegean coast that the great powers had denied her during the Nineteenth Century. In which Great War year did this event take place?

In 1914 the Ottoman Empire joined the Central Powers, while in the following year Italy joined the Western Allies.  These developments added at least two more fronts - the Alps and the Balkans - to the existing Western and Eastern Fronts.