When Antipater died in 319 BC, he left the regentship to
Polyperchon, excluding
Cassander, his son. Antigonus and the other dynasts refused to recognize Polyperchon, since it would have undermined their own ambitions. Antigonus entered into negotiations with Eumenes, but Eumenes had already been swayed by Polyperchon, who gave him authority over all other generals within the empire. Affecting his escape from Nora through trickery, Eumenes raised a small army and fled south into Cilicia. Antigonus did not move against Eumenes directly because he was tied up in northwestern Asia Minor campaigning against
Cleitus the White who had a large fleet at the Hellespont. Cleitus was able to defeat Antigonus's admiral
Nicanor in a sea battle but he was caught off guard the next morning when Antigonus and Nicanor launched a double assault by land and sea on his camp, Cleitus was taken completely by surprise and his entire force was captured or killed (see:
Battle of Byzantium). Meanwhile, Eumenes had taken control of Cilicia, Syria and Phoenicia, formed an alliance with
Antigenes and Teutamos, the commanders of the
Silver Shields and the
Hypaspists, and begun to raise a naval force on behalf of Polyperchon. When it was ready he sent the fleet west to reinforce Polyperchon, but off the coast of Cilicia it was met by Antigonus's fleet and changed sides. Antigonus had settled his affairs in Asia Minor and marched east into Cilicia, intent on doing battle with Eumenes in Syria. Eumenes somehow had advance knowledge of this and marched out of Phoenicia, through Syria into Mesopotamia, with the idea of gathering support in the
upper satrapies. Eumenes gained the support of Amphimachos, the satrap of Mesopotamia, then marched his army into Northern
Babylonia, where he put them into winter quarters. During the winter he negotiated with
Seleucus, the satrap of Babylonia, and
Peithon, the satrap of Media, seeking their help against Antigonus. Antigonus, finding out Eumenes had left his provinces, took some time securing Cilicia and northern Syria before he marched into Mesopotamia. Unable to sway Seleucus and Pheiton, Eumenes had left his winter quarters early and marched on
Susa, a major royal treasury, in
Susiana. In Susa, Eumenes sent letters to all the satraps to the north and east of Susiana, ordering them in the kings' names to join him with all their forces. When the satraps joined Eumenes he had a considerable force, with which he could look forward with some confidence to doing battle against Antigonus. Eumenes then marched southeastwards into Persia, where he picked up additional reinforcements Antigonus, meanwhile, had reached Susa and left Seleucus there to besiege the place, while he himself marched after Eumenes. At the river Kopratas, Eumenes surprised Antigonus during the crossing of the river and killed or captured 4,000 of his men. Antigonus, faced with disaster, decided to abandon the crossing and turned back northward, marching up into Media, threatening the upper satrapies. Eumenes wanted to march westward, and cut Antigonus's lines of supply, but the satraps refused to abandon their satrapies and forced Eumenes to stay in the east. In the late summer of 316 BC, Antigonus moved southward again in the hope of bringing Eumenes to battle and ending the war quickly. Eventually the two armies in southern Media and fought in the indecisive
Battle of Paraitakene. Antigonus, whose casualties were more numerous, force marched his army to safety the next night. During the winter of 316–315 BC, Antigonus tried to surprise Eumenes in Persia by marching his army across a desert and catching his enemy off guard, unfortunately, he was observed by some locals who reported it to his opponents. A few days later both armies drew up for battle. The
Battle of Gabiene was as indecisive as the previous battle at Parataikene. According to Plutarch and Diodorus, Eumenes had won the battle but lost control of his army's baggage camp thanks to his ally
Peucestas' duplicity or incompetence. This loss was especially severe for the Silver Shields; the camp contained loot they had accumulated over 30 years of successful warfare, as well as the soldiers' women and children. Approached by Teutamus, one of their commanders, Antigonus offered to return the baggage train in exchange for custody of Eumenes. The Silver Shields complied, arresting Eumenes and his officers and handing them over. The war was thus at an end. Eumenes was placed under guard while Antigonus held a council to decide his fate. Antigonus, backed up by his son Demetrius, was inclined to spare the prisoner, but the council overruled them and Eumenes was executed. As a result, Antigonus now was in possession of the empire's Asian territories, his authority stretching from the eastern satrapies to Syria and Asia Minor in the west. He seized the treasuries at
Susa and entered
Babylon. The governor of Babylon,
Seleucus, fled to Ptolemy and entered into a league with him,
Lysimachus and Cassander. ==The Third Diadochi War==