Simplify the following text for a Grade 10 native English-speaking person.
Original: Sophocles ' first artistic triumph was in 468 BC , when he took first prize in the Dionysia theater competition over the reigning master of Athenian drama , Aeschylus .
Simplified: Sophocles ' first great play was in 468 BC when he took first prize in the Dionysia theater competition over the reigning master of Athenian drama , Aeschylus .