Peter I of Yugoslavia (Alexander the Liberator)

Peter I (Serbian: Petar/Петар; 11 July [O.S. 29 June] 1844 – 16 August 1921) was the third Serbian ruler of the Karađorđević dynasty, the first Karađorđević king of Serbia, the last overall king of Serbia, and the first monarch of Yugoslavia. Since he was the king of Serbia during a period of great Serbian military success, he was remembered by Serbian people as King Peter the Liberator, and also known as Old King.

Peter was Karađorđe's grandson and third son of Persida Nenadović and Prince Alexander Karađorđević, who was forced to abdicate. Peter lived with his family in exile. He fought with the French Foreign Legion in the Franco-Prussian War. He joined as volunteer under the alias Peter Mrkonjić in the Herzegovina Uprising (1875–77) against the Ottoman Empire.

He married Princess Zorka of Montenegro, daughter of King Nicholas, in 1883. She gave birth to his five children, including Prince Alexander. After the death of his father in 1885, Peter became head of the Karađorđević dynasty. After a military coup d'état and the murder of King Alexander I Obrenović in 1903, Peter became King of Serbia. As king, he advocated a constitutional setup for the country and was famous for his libertarian politics.

King Peter was the supreme commander of the Serbian army. Because of his age, on 24 June 1914, he proclaimed his son, Alexander, heir-apparent to the throne, as regent. In the First World War he and his army retreated across Albania.