Ferdinand I of Bulgaria

Ferdinand I proclaimed Bulgaria's full independence from the Ottoman Empire, declaring himself Tsar. This ended Ottoman suzerainty and established Bulgaria as a sovereign kingdom.

Ferdinand I led Bulgaria into the First Balkan War against the Ottoman Empire. Bulgaria achieved major victories, capturing Adrianople and much of Thrace, significantly expanding its territory.

Ferdinand I ordered an attack on former allies Serbia and Greece, triggering the Second Balkan War. Bulgaria was defeated by a coalition including Romania and the Ottoman Empire, losing most of its gains.

After Bulgaria's defeat in World War I, Ferdinand I abdicated in favor of his son Boris III. He went into exile, ending his reign amid national crisis and territorial losses.