Another war soon broke out between the Diadochi. At the start of 318 BC
Arrhidaios, the governor of
Hellespontine Phrygia, tried to take the city of
Cyzicus. Antigonus, as the
Strategos of Asia, took this as a challenge to his authority and recalled his army from their winter quarters. He sent an army against Arrhidaios while he himself marched with the main army into
Lydia against its governor
Cleitus whom he drove out of his province. Cleitus fled to
Macedon and joined Polyperchon, the new Regent of the Empire, who decided to march his army south to force the Greek cities to side with him against Cassander and Antigonus. Cassander, reinforced with troops and a fleet by Antigonus, sailed to
Athens and thwarted Polyperchon's efforts to take the city. From Athens Polyperchon marched on
Megalopolis which had sided with Cassander and
besieged the city. The siege failed and he had to retreat losing a lot of prestige and most of the Greek cities. Eventually Polyperchon retreated to
Epirus with the infant King
Alexander IV. There he joined forces with Alexander's mother
Olympias and was able to re-invade Macedon. King
Philip Arrhidaeus, Alexander's half-brother, having defected to Cassander's side at the prompting of his wife,
Eurydice, was forced to flee, only to be captured in
Amphipolis, resulting in the execution of himself and the forced suicide of his wife, both purportedly at the instigation of Olympias. Cassander rallied once more, and seized Macedon.
Olympias was murdered, and Cassander gained control of the infant King and his mother. Eventually, Cassander became the dominant power in the European part of the Empire, ruling over Macedon and large parts of Greece. Meanwhile, Eumenes, who had gathered a small army in
Cappadocia, had entered the coalition of Polyperchon and Olympias. He took his army to the royal treasury at Kyinda in
Cilicia where he used its funds to recruit mercenaries. He also secured the loyalty of 6,000 of Alexander's veterans, the
Argyraspides (the Silver Shields) and the
Hypaspists, who were stationed in Cilicia. In the spring of 317 BC he marched his army to
Phoenica and began to raise a naval force on the behalf of Polyperchon. Antigonus had spent the rest of 318 BC consolidating his position and gathering a fleet. He now used this fleet (under the command of Nicanor who had returned from Athens) against Polyperchon's fleet in the
Hellespont. In a two-day
battle near Byzantium, Nicanor and Antigonus destroyed Polyperchon's fleet. Then, after settling his affairs in western
Asia Minor, Antigonus marched against Eumenes at the head of a great army. Eumenes hurried out of Phoenicia and marched his army east to gather support in the eastern provinces. In this he was successful, because most of the eastern
satraps joined his cause (when he arrived in
Susiana) more than doubling his army. They marched and counter-marched throughout
Mesopotamia,
Babylonia, Susiana and
Media until they faced each other on a plain in the country of the Paraitakene in southern Media. There they fought a great battle,
the battle of Paraitakene, which ended inconclusively. The next year (315) they fought another great but inconclusive battle,
the battle of Gabiene, during which some of Antigonus's troops plundered the enemy camp. Using this plunder as a bargaining tool, Antigonus bribed the Argyraspides who arrested and handed over Eumenes. Antigonus had Eumenes and a couple of his officers executed. With Eumenes's death, the war in the eastern part of the Empire ended. Antigonus and Cassander had won the war. Antigonus now controlled Asia Minor and the eastern provinces, Cassander controlled Macedon and large parts of Greece, Lysimachus controlled
Thrace, and Ptolemy controlled
Egypt, Syria,
Cyrene and
Cyprus. Their enemies were either dead or seriously reduced in power and influence. ==Third War of the Diadochi, 315–311 BC==