Mustafa Kemal Atatürk was born in 1881 in Thessaloniki, Greece. He became a military officer and fought in World War I, eventually leading the Turkish War of Independence against occupying forces. Atatürk established the Republic of Turkey in 1923 and served as its first president. As president, he modernized Turkey and introduced reforms to separate religion from state affairs and adopt a Western calendar and alphabet. Atatürk's principles of secularism, nationalism, populism, and modernization still guide Turkey today. He is regarded as the founder and hero of modern Turkey.