Constantine I of Greece was born on August 2, 1868, and became King of Greece in 1913. He was a member of the House of Schleswig-Holstein-Sonderburg-Glücksburg and was the son of King George I of Greece. His reign was marked by political turmoil and military conflicts, particularly during World War I. Constantine's pro-German stance during the war led to his abdication in 1917. He returned to the throne in 1920 but was forced to abdicate again in 1922 after Greece's defeat in the Greco-Turkish War. He spent his later years in exile and died on January 11, 1923.