Wars of the Diadochi > Fourth War of the Diadochi
Fourth War of the Diadochi
The peace was short lived again, as soon the Fourth War of the Diadochi (308–301 BC) was underway. Ptolemy I Soter had begun expanding the territory of the Ptolemaic Kingdom into the Aegean Sea along with taking over Cyprus. During this period Seleucus I Nicator went on a massive campaign through the east to consolidate his power in the vast holdings of the ancient Achaemenid Empire into his new Seleucid Empire.
The war broke out when Antigonus I Monophthalmus sent his son Demetrius I Poliorcetes to regain control of Greece, taking the city of Athens in 307 BC to start. He expelled Demetrius of Phaleron who was the governor of Cassander and then turned his attention to Ptolemy who was trying to gain a larger foothold in Greece.
Demetrius invaded Cyprus and defeated Ptolemy at the Battle of Salamis in 306 BC, prompting Antigonus to launch an invasion of Egypt. In 306 BC he attempted just that but storms in the Mediterranean Sea prevented supplies from reaching his army and he was forced to retreat. With Seleucus campaigning in the East and both Cassander and Ptolemy weakened, Antigonus planned to consolidate his control over Greece and turned his attention to the island city-state of Rhodes in 305 BC. The island of Rhodes was reinforced with soldiers from the armies of Ptolemy, Lysimachus, and Cassander however, so this was going to be a daunting task.
See Siege of Rhodes
Eventually the people of Rhodes simply wanted to remain out of a prolonged conflict and be allowed to continue their commerce through the region. Therefore they arranged an agreement with Demetrius to support him and Antigonus against all of the other Hellenistic Kingdoms in exchange this does not include the Ptolemaic Kingdom and Ptolemy I which was one of their great trading partners and allies.
Ptolemy would eventually earn his title of Soter meaning "savior" for his following role in the defense and reinforcement of Rhodes. However, the move left Demetrius open to attack Cassander in Greece. After the defeat of Cassander he would establish a new Hellenic League with himself as general. After facing many defeats at the hands of Antigonus the beaten Cassander sued for peace, an offer which was rejected. From here Antigonus would invade Thessaly in an attempt to chase Cassander and the two fought in occasional skirmishes that did not have any decisive outcomes.
Eventually Cassander was able to call in reinforcements and his allies including Lysimachus invaded Anatolia which forced Demetrius to leave Thessaly to help reinforce his father. The combined alliance of Cassander and Lysimachus was soon able to take over much of western Anatolia but was soon isolated during the Battle of Ipsus.
The Battle of Ipsus in 310 BC was the decisive battle of the Fourth Diadochi War that saw the destruction of Antigonus I Monophthalmus's forces along with his death in combat. The battle was initially fought between Lysimachus and Antigonus however, the arrival of Seleucus I and his army saw the surprise defeat of Antigonus.
Demetrius I Poliorcetes was forced to flee back to Greece in order to maintain leadership there and most of the territory in Anatolia controlled by Antigonus was divided up between Lysimachus and Seleucus. Lysimachus took Anatolia and Seleucus took the rest with the exception of Cassander's brother Pleistarchus gaining the territories of Cilicia and Lycia.
Struggle Over Macedon
See Syrian Wars
While the Fourth Diadochi War would conclude the series of wars known as the Wars of the Diadochi the fighting between the descendants of the various Hellenistic Kingdoms would occur until they would be conquered by the Roman Empire and Parthia. One of the major series of these wars was known as the Syrian Wars and occurred between the Ptolemaic Kingdom and the Seleucid Empire over the territory known as Coele-Syria.