Egypt mattered. Though no emperor since Diocletian had travelled to the country, its tax revenues accounted for roughly a third of the overall output of the prefecture of the East, grain deliveries formed a significant portion of the capital’s provision, and it was protected by roughly 20–30,000 men.[1] How, therefore, Byzantine forces were defeated by a 15,000-strong Arab force has continued to bewilder historians.[2] One of the most common reasons given is sectarian strife. More specifically, the rivalry between Cyrus the Monothelete patriarch and Benjamin his Monophysite opposite number. Coptic martyrologies describe a full-scale persecution by Cyrus, a man who appears to have paid large sums of solidi to the Arabs to avoid an invasion, and who clearly doubted the ability of the city to defend itself (even defending his opinion before Heraklios at Constantinople in 640). The theory continues that the Egyptian countryside, the chora, was therefore utterly indifferent to who ruled the cities as taxes sent to Monothelete enemies were as bad as paying the same to tawhid-obsessed Arabs. The allegations appear, again, to be confirmed by the lack of Christian martyrs, a very different picture to either Syria or Gaza.[3]
The problem with much of this that there is only one contemporary eyewitness, the Monophysite bishop John of Nikiou. And his Coptic account is preserved in a flawed Ethiopian translation. In its existing form many passages are confusing and may contain errors that concern both chronology and prosopography. Other Byzantine historians like Nikephoros and Theophanes the Confessor report on the same events but only tangentially and use sources like Theophilus of Edessa who probably wrote in northern Syria.
This means it’s hard to to cross-reference Coptic martyrologies with any certainty. It does seem, however, that these are at the very least questionable. Indeed, they’re largely eschatological or hortative texts that seek to frame sufferings according to hagiographical agendas and topoi.[4] There are similar issues with Arab sources. Even the earliest one wrote one and a half centuries after the event. Both of them project later conditions backwards in time, often exaggerating the cooperation of the Copts to de-escalate contemporary conflicts.
While the polarisation of the Monothelites and Monophysites is likely, there’s no clear evidence that it poisoned relations to the extent they welcomed the Arabs. Perhaps the latter hoped for a lower tax burden but there’s no evidence the Islamic army propagated such a claim. It’d be quite odd for the Egyptians to suddenly become a fifth column. Very few soldiers were recruited from outside the country (only a campaign against the Blemmyans in the sixth century recruited outsiders in number). Furthermore, Egyptian aristocrats had been Monophysites for generations and not felt compelled to seek a home outside the empire.
Though the military performance shouldn’t be downplayed (especially as Alexandria resisted the siege fervently and for a considerable period), it’s probably the most obvious reason for Egypt’s quick collapse.[5] The fact remains the Arabs never confronted a force of 30,000 Byzantines. There were four commanders in Egypt and they busied themselves feuding over seniority, while the only other potential Roman figurehead – the Monothelete patriarch – demanded a surrender. Such a fragmentation of defence meant the Arabs only ever confronted a quarter of Byzantine forces at most. Extra troops would have been a serious help, hence the seriousness of Constans II’s accusation against Maximos the Confessor when the monk stood charged with dissuading the commander of Africa from sending troops to Egypt’s aid. Though he denied it as slander, the emperor had him convicted and exiled to Thrace.[6]
[1] F. Mitthof, Annona Militaris (2001), vol. 1, 217-31.
[2] H. Kennedy, Armies of the Caliphs (2001) 11-20, 62-9).
[3] J. van Ginkel, “Perception and Presentation of the Arab Conquest,” The Encounter of Eastern Christianity with Early Islam, Eds. M. Swanson and D. Thomas (2006) 171-84.
[4] J. Jeijer, “Coptic Historiography…” Medieval Encounters 1 (1996) 67-98.
[5] . Mosjov, Alexandria Lost (2010).
[6] J. Howard-Johnston, Witnesses to a World Crisis (2010) 157-62.