In Greek mythology , the son of the king of Phoenicia, brother of Europa , and founder of Thebes .
When Zeus carried off Europa, Cadmus was sent to find her. The Delphic oracle ordered him to end his search, follow a cow, and build a town where it lay down. That town became Thebes. He built the citadel of Thebes with the help of fierce armed men who sprang up where he sowed the teeth of a dragon he had slain. He married Harmonia, daughter of Ares and Aphrodite , and their five children included Semele . Cadmus was said to have brought the alphabet to Greece.