Initially a secondary player in the power struggles following Alexander's death, Seleucus rose to become the total ruler of Asia Minor, Syria, Mesopotamia, and the Iranian plateau, assuming the title of basileus (king).

[5] Furthermore, the Seleucid Empire received a considerable military force of 500 war elephants with mahouts, which would play a decisive role against Antigonus at the Battle of Ipsus in 301 BC.

Appian wrote of an incident in which a wild bull that was about to be sacrificed by Alexander broke free of its bounds, and Seleucus managed to recapture the animal by grabbing and holding unto its horns with his bare hands.

It was said Antiochus told his son before he left to battle the Persians with Alexander that his real father was actually the god Apollo.

[2] By the time of the Indian campaigns beginning in late in 327 BC, he had risen to the command of the elite infantry corps in the Macedonian army, the "Shield-bearers" (Hypaspistai, later known as the "Silvershields").

It is said by Arrian that when Alexander crossed the Hydaspes river on a boat, he was accompanied by Perdiccas, Ptolemy I Soter, Lysimachus and also Seleucus.

After Alexander's death (323 BC), when the other senior Macedonian officers unloaded their "Susa wives" en masse, Seleucus was one of the very few who kept his wife, and Apama remained his consort (later Queen) for the rest of her life.

In the first of these episodes, he participated in a sailing trip near Babylon, where Alexander's diadem was blown off his head and landed on some reeds near the tombs of Assyrian kings.

[clarification needed insufficient details and context] In the final story, Seleucus reportedly slept in the temple of the god Serapis shortly before Alexander's death in the hope that his health might improve.

Seleucus was chosen to command the Companion cavalry (hetairoi) and appointed first or court chiliarch, which made him the senior officer in the Royal Army after the regent and commander-in-chief Perdiccas.

It is not certain how Seleucus took Babylon from Docimus, but according to one Babylonian chronicle an important building was destroyed in the city during the summer or winter of 320 BC.

The satraps in Susa had apparently accepted Eumenes' claims of his fighting on behalf of the lawful ruling family against the usurper Antigonus.

She held great respect among the Macedonian army but lost some of this when she had Philip III and his wife Eurydice killed as well as many nobles whom she took revenge upon for supporting Antipater during his long reign.

Alexander IV, still a young child, and his mother Roxane were held guarded at Amphipolis and died under mysterious circumstances in 310 BC, probably murdered at the instigation of Cassander to allow the diadochs to assume the title of king.

The allies sent a proposition to Antigonus in which they demanded shares of his accumulated treasure and of his territory, with Phoenica and Syria going to Ptolemy, Cappadocia and Lycia to Cassander, Hellespontine Phrygia to Lysimachus, and Babylonia to Seleucus.

Seleucus hid his armies in the marshes that surrounded the area where Nicanor was planning to cross the Tigris and made a surprise attack during the night.

[34] Over the course of nine years (311–302 BC), while Antigonus was occupied in the west, Seleucus brought the whole eastern part of Alexander's empire as far as the Jaxartes and Indus Rivers under his authority.

Ptolemy, Lysimachus, Cassander and Seleucus, the other four principal Macedonian chiefs, soon followed and assumed the title and style of basileus (king).

The Persian provinces in what is now modern Afghanistan, together with the wealthy kingdom of Gandhara and the states of the Indus Valley, had all submitted to Alexander the Great and become part of his empire.

According to the Roman historian Appian: [Seleucus was] always lying in wait for the neighboring nations, strong in arms and persuasive in council, he acquired Mesopotamia, Armenia, 'Seleucid' Cappadocia, Persis, Parthia, Bactria, Arabia, Tapouria, Sogdia, Arachosia, Hyrcania, and other adjacent peoples that had been subdued by Alexander, as far as the river Indus, so that the boundaries of his empire were the most extensive in Asia after that of Alexander.

Seeking to hold the Macedonian territories there, Seleucus thus came into conflict with the emerging and expanding Mauryan Empire over the Indus Valley.

[42] The two leaders ultimately reached an agreement,[43] and through a treaty sealed in 303 BC,[44] Seleucus abandoned the territories he could never securely hold in exchange for stabilizing the East and obtaining elephants, with which he could turn his attention against his great western rival, Antigonus Monophthalmus.

[43] The 500 war elephants Seleucus obtained from Chandragupta were to play a key role in the forthcoming battles, particularly at Ipsus[45] against Antigonus and Demetrius.

Alexander [III 'the Great' of Macedon] took these away from the Arians and established settlements of his own, but Seleucus Nicator gave them to Sandrocottus [Chandragupta], upon terms of intermarriage and of receiving in exchange five hundred elephants.

[48][49] This would tend to be corroborated archaeologically, as concrete indications of Mauryan influence, such as the inscriptions of the Edicts of Ashoka which are known to be located in, for example, Kandhahar in today's southern Afghanistan.

— Pliny, Natural History VI, 23[52] The span of control of the Mauryas is also questioned by present-day archaeologists, and the idea that the ceded territory included all of Aria and Gedrosia (Balochistan) seems unlikely.

[55] In addition to this matrimonial recognition or alliance, Seleucus dispatched an ambassador, Megasthenes, to the Mauryan court at Pataliputra (Modern Patna in Bihar state).

[66] Seleucus nominated his son Antiochus I as his co-ruler and viceroy of the eastern provinces in 292 BC, the vast extent of the empire seeming to require a double government.

Excavations at the site of Dura-Europos in Syria, for instance, uncovered a cult relief from a temple showing Seleucus, as the founder of the city, crowning the Gad of Dura.

[71] Clearer evidence that the city considered Seleucus to be its founder come from a fragmentary papyrus document, P. Dura 32, which designates Dura-Europos as "the colony of the Europeans of Seleucs Nicator".