Ferdinand I of Bulgaria (d. 1948)
Ferdinand (Bulgarian: Фердинанд I; 26 February 1861 – 10 September 1948), born Ferdinand Maximilian Karl Leopold Maria of Saxe-Coburg and Gotha (Фердинанд Максимилиан Карл Леополд Мария Сакс-Кобург и Гота), was the second monarch of the Third Bulgarian State, firstly as ruling prince (knyaz) from 1887 to 1908, and later as king (tsar) from 1908 until his abdication in 1918. Under his rule Bulgaria entered the First World War on the side of the Central Powers in 1915.