Diadochi
In 315 BC, he joined Cassander, Ptolemy I Soter and Seleucus I Nicator against Antigonus I Monophthalmus, who, however, diverted his attention by stirring up Thracian and Scythian tribes against him. In 309 BC, he founded Lysimachia in a commanding situation on the neck connecting the Chersonese with the mainland. He followed the example of Antigonus I in taking the title of king.
In 306/305 BC, he assumed the title of "King", which he held until his death at Corupedium in 282/1 BC.
In 302 BC, when the second affiance between Cassander, Ptolemy I and Seleucus I was made, Lysimachus, reinforced by troops from Cassander, entered Asia Minor, where he met with little resistance. On the approach of Antigonus I he retired into winter quarters near Heraclea, marrying its widowed queen Amastris, a Persian princess. Seleucus I joined him in 301 BC, and at the battle of Ipsus Antigonus I was defeated and slain. His dominions were divided among the victors. Lysimachus' share was Lydia, Ionia, Phrygia and the north coast of Asia Minor.
Feeling that Seleucus I was becoming dangerously great, Lysimachus now allied himself with Ptolemy I, marrying his daughter Arsinoe II of Egypt. Amastris, who had divorced herself from him, returned to Heraclea. When Antigonus I’s son Demetrius I renewed hostilities (297 BC), during his absence in Greece, Lysimachus seized his towns in Asia Minor, but in 294 BC concluded a peace whereby Demetrius I was recognized as ruler of Macedonia. He tried to carry his power beyond the Danube, but was defeated and taken prisoner by the Getae king Dromichaetes (Dromihete), who, however, set him free on amicable terms. Demetrius I subsequently threatened Thrace, but had to retire due to a sudden uprising in Boeotia, and an attack from the King Pyrrhus of Epirus.
In 288 BC, Lysimachus and Pyrrhus of Epirus in turn invaded Macedonia, and drove Demetrius I out of the country. Lysimachus left Pyrrhus of Epirus in possession of Macedonia with the title of king for around seven months before Lysimachus invaded. For a short while the two ruled jointly but in 285 BC Lysimachus expelled Pyrrhus.
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