Cambyses II

Cambyses II inherited the Achaemenid throne in 530 BCE when his father Cyrus the Great fell fighting the Massagetae in Central Asia; he'd already served as governor of northern Babylonia and briefly as co-ruler. His reign pivoted on a single campaign: the invasion of Egypt, where he crushed Pharaoh Psamtik III at the Battle of Pelusium in 525 BCE and pushed west into Cyrenaica along the Libyan coast. Seven years in, a revolt erupted in Persia and forced him to abandon Egypt in the spring of 522 BCE. Somewhere en route to Syria he took a thigh wound that turned gangrenous; three weeks later he died in Agbatana, childless. His younger brother Bardiya took the throne and held it briefly before Darius overthrew him and carried the empire forward.