The Battle of Corupedium
Background King Lysimachus had ruled Thrace for decades and parts of Western Turkey ever since the Battle of Ipsus.
King Seleucus ruled the Seleucid Empire, including lands currently covered by Eastern Turkey, Syria, Lebanon, Israel, Iraq and Iran.
In 284 BC, Lysimachus, on the urging of his new wife, Arsinoe (daughter of Ptolemy), put his eldest son to death on the charge of conspiring to seize the throne. This atrocious deed aroused great indignation. Many of the cities of Asia revolted, and Lysimachus’s most trusted friends deserted him. It was the perfect pretense that Seleucus needed to invade the territory of Lysimachus.
The armies of Lysimachus and Seleucus met at the decisive battle of Corupedium in 281 BC. Seleucus’ army defeated and killed Lysimachus. After some days his body was found on the field, only his faithful dog was still by his side, protecting his body from the vultures.
The victorious Seleucus was now master of the domains of Lysimachus and had already begun preparing to take on Macedon, still held by the descendents of Antigonus Monophthalmos. He also was protecting the eldest son of Ptolemy I of Egypt: Ptolemy Keraunos. Ptolemy Keraunos had been repudiated by his father who had instead chosen his teenage son from his newest wife as his successor. Thus Seleucus had a somewhat legitimate excuse to meddle in the affairs of his former friend Ptolemy's kingdom aswell if he had chosen. For a moment Seleucus looked unstoppable, the dream of re-uniting the Empire of Alexander seemed achievable. But it was not to be, whilst Seleucus and his dependent, Ptolemy Keraunos were traveling together through Thrace, Keraunos stabbed Seleucus in the back, killing him instantly.