Page "Anthemius" Paragraph 6

In October 456, in fact, the Western Emperor Avitus had been deposed ; it is probable that Marcian considered Anthemius as successor, but the Eastern Emperor died in January 457 before choosing his colleague.

Therefore both empires had no Emperor, and the power was in the hands of the Western generals, Ricimer and Majorian, and of the Eastern Magister militum, the Alan Aspar.

As Aspar could not sit on the throne because of his barbaric origin, he opposed Anthemius whose prestige would have made him independent and chose a low-ranking military officer, Leo ; in the West, as his barbaric origin barred Ricimer from the throne, it was Majorian who received the purple.