King Alexander I of Serbia, also known as Alexander I Obrenović, ruled from 1903 until his assassination in 1934. He was born on December 14, 1888, and became king after a coup that ended the rule of the Obrenović dynasty. His reign was marked by efforts to modernize Serbia and strengthen its military. Alexander I was known for his authoritarian style of governance and his attempts to unify the Yugoslav peoples. He faced significant political challenges, including opposition from various factions. His reign ended tragically when he and his family were murdered in a coup led by Croatian nationalists in 1934.