Constantine I of Greece, born on 2 August 1868 in Athens, was the eldest son of King George I and Queen Olga. He was the first Greek-born heir apparent, and his birth was celebrated with great enthusiasm. He was christened Constantine on 12 August and held the title of Diádochos, or Crown Prince. Educated by prominent professors, he enrolled in the Hellenic Military Academy in 1882 and later studied in Germany, where he served in the Imperial Guard. By 1890, he had risen to the rank of Major General and commanded the 3rd Army Headquarters in Athens.In January 1895, Constantine intervened in a protest against tax policy, leading to political turmoil and the resignation of Prime Minister Charilaos Trikoupis. He later played a significant role in organizing the 1896 Summer Olympics in Athens, serving as president of the organizing committee and securing funding for the restoration of the Panathinaiko Stadium.As commander-in-chief during the Greco-Turkish War of 1897, Constantine faced a humiliating defeat, which diminished the monarchy's popularity. This discontent contributed to the Goudi coup in 1909, resulting in his temporary dismissal from military command. He was reinstated by Prime Minister Eleftherios Venizelos, who sought to restore confidence in the monarchy.In 1912, with the formation of the Balkan League, Constantine became Chief of the Hellenic Army. He led Greek forces to victory in the First Balkan War, capturing Thessaloniki and Ioannina, which significantly expanded Greek territory. Following the assassination of his father on 18 March 1913, Constantine ascended to the throne. He successfully commanded Greek forces during the Second Balkan War against Bulgaria, further increasing Greece's territorial gains.During World War I, a rift developed between Constantine and Venizelos over Greece's involvement in the conflict. Constantine favored neutrality, while Venizelos sought alignment with the Allies. This disagreement led to the National Schism, dividing the country between royalists and Venizelists. Under pressure from the Allies, Constantine abdicated on 11 June 1917, and his son Alexander became king.After Alexander's death in 1920 and Venizelos' electoral defeat, Constantine was restored to the throne on 19 December 1920. He continued the war against the Kemalist forces in Asia Minor, initially achieving some success. However, a poorly planned campaign led to a disastrous defeat in August 1922. Following a military revolt, Constantine abdicated for the second time on 27 September 1922, and his eldest son George II succeeded him.Constantine spent his final months in exile in Italy, where he died on 11 January 1923 in Palermo from heart failure. He was buried in the Russian Church in Florence, and his wife, Sophie of Prussia, was never allowed to return to Greece.