Thucydides is the founder of political historiography. He was about 30 years old when the Peloponnesian War broke out in 431 BC, a decades-long power struggle between Athens and Sparta, which ultimately saw Athens—and with it, democracy—defeated by Spartan kingship. Thucydides had found his life’s theme here. However, before he became the chronicler of the conflicts between the two factions, he participated in them himself. In 425/4 BC, he held the high military office of strategos until a failure led to his exile. He then lived in exile for 20 years and only returned to Athens after the war ended.