Seleukos was born to Antiochos and Laodike of Europos in Macedonia sometime between c. 358 and c. 354 BC. Both he and his father were part of the military aristocracy that contributed to the rise of Macedonian power under Philip II and Alexander the Great, although they were not as close to the kings as men like Ptolemy and Lysimachos.
During Alexander's eastern campaigns Seleukos was given command of the prestigious argyraspides ('Silver Shields') regiment. Shortly after Alexander's death in 323 Seleukos was appointed chiliarch (vizier) by the Macedonian general, Perdikkas. The latter claimed to have been given the right to rule the empire until Alexander's pregnant widow should give birth to an heir. Perdikkas also believed that it was his right to apportion the various administrative districts (satrapies) of the empire to deserving generals.
Jealous of Perdikkas' power and concerned about his inability to control many of the governors (satraps), in 321 Seleukos, leading a cabal of officers, murdered him.
Following the murder, Seleukos was appointed satrap of Babylonia during a conference of the generals in Syria. At the same meeting Antigonos Monophthalmos ('the One-Eyed') was given special powers to hunt down and destroy Eumenes of Kardia, a surviving Greek adherent of Perdikkas who was largely opposed to breaking up the empire among the generals.
After the removal of Eumenes, Antigonos' ambitions turned to imperialism and the restoration of Alexander's fragmented empire under his own authority. He threatened Seleukos in 315 BC, causing the satrap to flee Babylon and join the court of Ptolemy in Egypt where he became a nauarch (naval commander) charged with harassing Antigonid coastal positions.
In 312 BC Seleukos helped Ptolemy to victory over Antigonos' son, Demetrios Poliorketes ('the Besieger'), at the battle of Gaza. He used the confused aftermath of the battle to cover his return to and reestablishment in Babylon. Although Antigonos and Demetrios made several further attempts to remove Seleukos between 311 and 308 BC he was able to maintain control with the aid of the loyal Babylonians.
During a brief period of peace with Antigonos Seleukos campaigned in the east, forcing the satraps there to recognized his suzerainty. He also concluded a treaty with Chandragupta Maurya of India who gave him a gift of 500 war elephants.
In 305/4 BC Seleukos proclaimed himself king following the precedent established by his contemporaries: Antigonos, Ptolemy, Kassander and Lysimachos. Disturbed by the growing power of Antigonos in Asia Minor, the Levant and Greece, the latter three kings joined with Seleukos in a defensive coalition. At Ipsos in 301 BC the alliance was successful in defeating and killing Antigonos, leaving Seleukos to claim Syria where he founded the western capital of Antioch-on-the-Orontes. Shortly after the fall of Antigonos Seleukos founded his eastern capital at Seleukeia-on-the-Tigris. For his key role in the victory he was also supposed to receive Phoenicia and Palestine, but Ptolemy garrisoned the cities there before Seleukos could claim them. The dispute over this territory would pit Seleukid and Ptolemaic kings against one another for almost two centuries.
From 294 to 286 Seleukos was at war with Demetrios who had survived the debacle of Ipsos and continued to threaten the stability of the kings. The troops of Demetrios, however, were wearied by their long campaigning and Seleukos was ultimately able to defeat them and capture their leader in Kilikia. Although Seleukos kept him in honourable captivity Demetrios despaired and drank himself into oblivion.
Meanwhile, Lysimachos had made himself so unpopular in Asia Minor that his subjects invited Seleukos to remove him. The situation reached its climax in 281 when Lysimachos was defeated and killed at the battle of Koroupedion. Seleukos immediately consolidated his power in Asia Minor and advanced to take possession of Lysimachos' territory in Macedonia. In this year Seleukos was close to holding the entire empire of Alexander in his own name. But it was not to be.
At this high point of his career
Seleukos was struck down
by the blade of the assassin. Ptolemy Keraunos, a refugee from the
Ptolemaic
court to whom Seleukos had given asylum, murdered his benefactor on the
shores of Thrace and briefly usurped the diadem in Macedonia. Asia
Minor
and the east was left to Seleukos' son and heir Antiochos
I Soter.
View coins of Seleukos I Nikator.