Battle of Ipsus
Cassander's power was challenged by Antigonus, ruler of Anatolia, who promised the Greek cities that he would restore their freedom if they supported him. This led to successful revolts against Cassander's local rulers. In 307 BC, Antigonus's son Demetrius captured Athens and restored its democratic system, which had been suppressed by Alexander. But in 301 BC a coalition of Cassander and the other Hellenistic kings defeated Antigonus at the Battle of Ipsus, ending his challenge.