After a four-month interregnum, Glycerius was proclaimed as emperor in March 473 by Gundobad, the magister militum (master of soldiers) and power behind the throne.

[3] He rose to the office of comes domesticorum (commander of the palace guard), and likely served as such during the reign of Western Roman Emperor Olybrius (r. 472).

[6][7] Ricimer died on 18 August 472, forty days after deposing Anthemius, and was succeeded as magister militum and kingmaker by his Burgundian nephew Gundobad.

[2][4][12] Mathisen comments that these actions to defend the empire may be the reason that Glycerius receives a generally favorable reception in Roman and Byzantine sources.

[4]Mathisten states that the aforementioned injuries to Glycerius' mother may have been in reaction to his bribery of Videmir, but remarks that "such measures were a regular part of imperial policy", and speculates that the attackers may have been soldiers, explaining their lack of punishment.

[12] The 7th-century historian John of Antioch states that Leo made the decision to remove Glycerius after hearing that he had assumed the throne of the Western Roman Empire, but Mathisen comments that Leo must have hesitated for some time, as the actual invasion was delayed by the onset of winter, and Julius Nepos was forced to wait until the beginning of spring to launch his invasion.

[12][22][23] The historian John Michael O'Flynn states that the "circumstances surrounding this speedy overthrow are obscure and, at first sight, puzzling", noting that while the forces of Nepos were likely small, Gundobad made no moves to counter them, but rather "disappeared entirely from the Italian scene."

Additionally, Glycerius seems to never have attracted the favor of the Roman Senate or the Gallo-Roman aristocracy, which would make the decision to back him, and therefore alienate both, far less palatable for Gundobad.

[24] Notably, as king of Burgundy, Gundobad (r. 473/474–516) enjoyed warm relations with the Eastern Roman Empire, which he served as a foederatus (treaty subject).

[22][23] Mathisen suggests the alternatives that Gundobad was attempting to raise further troops in Gaul, or that he left to ensure he received his inheritance after the death of his father, King Gondioc (r. 437–473).