Glaucias is first mentioned as bringing a considerable force to the assistance of Bardylis' son Cleitus, an Illyrian prince who revolted against Alexander the Great, in the battle of Pelium 335 BC.

They were, however, both defeated, and Cleitus was forced to take refuge within the Taulantian territories, whither Alexander did not pursue him, his attention being called elsewhere by the news of the revolt of Thebes.

By this measure he gave offence to Cassander, who sought to gain possession of Epirus for himself, and who in vain offered Glaucias 200 talents to give up the child.

Not long after, the Macedonian king invaded his territories, and defeated him in battle; but though Glaucias bound himself by the treaty which ensued to refrain from hostilities against the allies of Cassander, he still retained Pyrrhus at his court, and, after the death of Alcetas II of Epirus, in 307 BC, he took the opportunity to invade Epirus with an army, and establish the young prince, then 12 years old, upon the throne.

Philip was wounded and lost part of his close group of friends, finally contenting himself with the possession of the Illyrian region of Dassaretia.

He therefore pitched and fortified a camp on the river Eordaicus in full sight of the Illyrians, and next morning he moved his army up to the wall of Pelion.

He acted at once, sending his baggage train of horse-drawn wagons with an escort of cavalry under Philotas to round up supplies in the plain of Koritsa.

The Macedonians paraded on the flat plain, without its baggage train, but with its catapults, which led the Illyrians under Glaucias and Cleitus to expect an assault upon the walls of Pelion.

Glaucias had a grandstand view from the battlements of Pelion and the surrounding heights, was amazed by the precision of the drill and bewildered by the changing movements.

Suddenly Alexander formed the left front of the phalanx into a wedge (embolon) and charged Cleitus' troops on the nearest slopes.

The Illyrians had assumed that Alexander had fled for good, so had bivouacked their men over a wide area and had not built field defences or mount guards.

Cleitus and that part of his army under his immediate command, escaped into Pelion, but the rest suffered the thoroughness of the cavalry pursuit which continued to the mountains of Glaucias' state, some 95 km away.

[4] In 317 BC Glaucias was in league with the two Greek colonies of Epidamnus and Apollonia as well as with the island of Corcyra while Cassander of Macedon was at a low ebb.

After he advanced north and crossed the Genusus river, Cassander defeated Glaucias' army, and by simulating a feigned retreat he tricked the people of Epidamnus.

In 317 BC, six years after the death of Alexander and with power in Macedonia in the hands of Cassander, Glaucias offered asylum to the infant Pyrrhus after the expulsion of his father Aeacides from his kingdom among the Molossians.

Plutarch describes that after eluding their pursuers, they arrived in Illyria, and finding Glaucias at home with his wife, they placed the baby on the ground between their feet.

[2] The date of Glaucius' death is not mentioned, but it appears that he was still reigning in 302 BC, when Pyrrhus travelled to his court, to be present at the marriage of one of his sons.