Battle of Ipsus
After the death of Alexander the Great in 323 BC, Philetaerus became embroiled in the struggle for supremacy, called the Wars of the Diadochi (diadochi means "successors" in Greek) among Alexander's regional governors, Antigonus in Phrygia, Lysimachus in Thrace, and Seleucus in Babylonia (among others). Philetaerus served first under Antigonus. He then shifted his allegiance to Lysimachus (ruler of Thrace from 323 BC to 281 BC), who, after Antigonus was killed at the Battle of Ipsus in 301 BC, made Philetaerus commander of Pergamon, where Lysimachus kept a treasury of nine thousand talents of silver.