Séparation ou cumul ? P ouvoir civil et autorité militaire dans les provinces égyptiennes de Gallien à la conquête arabe

In the third century, a series of crises led to extraordinary military appointments (duces, correctores), which sidelined the authority of the civil governor. Diocletian's separation of the two forms of service — armata et inermis, civil and military - solidified under Constantine into a provincial administrative structure which disassociated civil and military authority. This separation lost its force after the middle of the fourth century, in favour of the military powers which encroached upon the powers of the civil governor. The history of the relationship between the two authorities is by no means as straightforward as it is commonly represented. Moreover, even when the separation of powers was in force, it did not entail a complete divide between the two authorities, which were led to co-operate in a variety of situations. The appointment of the Comes Aegypti under Theodosius created in the military sphere a rank equivalent to the 'vicariate' of the Augustalis, further extending the equivalence between military and civil structures. On many occasions, the tension between the two spheres was resolved by a combination of powers-for example, in the last quarter of the fifth century, the powers of the comes and the Augustal Prefect - but not on a permanent basis. Justinian took the opposite route, altering the balance in favour of the civil power while reinforcing the identity of the province (by a classicising return to the concept of the governor of the imperial period?). The effects of this double orientation - restoring authority to the civil power and reinforcing provincial autonomy — were disastrous for the defence of Byzantine Egypt, as was shown by the conquest of Egypt in 641, after that of Syria. The examples of Senecio (P. Abinn. 1), Flavius Eleutherius (SB VIII, 7840), the topoteretes Zoilos (P. Ross. Georg. V, 30) and the generals who commanded against the Arab attack (John of Nikiu) are examined in detail.