The accession to the purple on November 20, 284, of Diocletian, the lower-class, Greek-speaking Dalmatian commander of Carus's and Numerian's household cavalry (protectores domestici), marked a major departure from traditional Roman constitutional theory regarding the Emperor, who was nominally first among equals during the Principate. Diocletian introduced Oriental despotism into Imperial dignity; whereas before Emperors had worn only a purple toga (toga picta) and greeted with deference, Diocletian wore jewelled robes and shoes, and required those who greeted him to kneel and kiss the hem of his robe (adoratio). In many ways, Diocletian was the first monarchical Emperor, and this is symbolised by the fact that the word dominus ("Lord") rapidly replaced princeps as the favoured word for referring to the Emperor.
The office of Roman Emperor underwent significant turbulence in the fourth and fifth centuries, after assuming the trappings of Eastern despotism during the Dominate. In the West, its holders became puppets of a succession of barbarian kings. In the East, it consolidated its new autocratic trappings as it transformed into the office of Byzantine Emperor.