401, the diocese came under a vicarius of the praetorian prefecture of the East, with the title of praefectus augustalis, and included six provinces:[2][3] Parallel to the civil administration, the Roman army in Egypt had been placed under a single general and military governor styled dux (dux Aegypti et Thebaidos utrarumque Libyarum) in the Tetrarchy.

[5] The comes limitis Aegypti enjoyed great power and influence in the diocese, rivalling that of the praefectus augustalis himself.

From the 5th century, the comes is attested as exercising some civilian duties as well, and from 470 on, the offices of comes and praefectus augustalis were sometimes combined in a single person.

[6] This tendency to unite civil and military authority was formalized by Justinian I in his 539 reform of Egyptian administration.

The diocese was effectively abolished, and regional ducats established, where the presiding dux et augustalis was placed above the combined civil and military authority:[6][7] Taken from the Prosopography of the Later Roman Empire (except for Theognostus):