Having introduced A.J. Butler in Part I, and discussed his works on Coptic churches and practices, I want to turn today to the works for which he is best known: his 1902 study of the Arab Conquest of Egypt, and two sequels in which he followed up on the original as new sources became available.
The period of the Arab Conquests of the Middle East in the early Islamic period has notoriously created challenges for historians. Traditional Arab historiography derived its fundamental methodology from hadith criticism, the method devised to determine the practices of the Prophet Muhammad through anecdotal evidence (hadith) documented by a chain of transmission (isnad) of the form "I heard from so-and-so who was taught by so-and-so who heard it from his uncle so-and-so who heard it from the Prophet in person." Recognizing that transmitters might invent these chains, scholars known as mutahaddithun studied biographies and other data to determine if each link in the chain held up (Were they alive at the same time? Were they ever in he same place?) Many modern critics have raised doubts about the method, but Arab historians expanded it to documenting the early years of the faith. Though most of our systematic Arab history dates from a later period, the second and third centuries AH, the traditional chains offer a far more textured and detailed account than is available for, say, Western Europe in the same era.
The problem is that, when an Arab historian encountered seemingly inconsistent or contradictory versions, he simply listed them both, even if they muddled the chronology or the narrative. For the conquest period, the standard and massive work of al-Tabari follows at least two distinct traditional lines (each with their own internal variations). For the conquest of Syria-Palestine, the chronology and command structure and even the dates of battles is very muddled. Nineteenth-century Orientalist scholars such as Michael Jan de Goeje in Mémoire sur la Conquête de la Syrie and Prince Leone Caetani in his meticulous Annali dell'Islam hammered out a sort of "received version" of the chronology and sequence of events, that dominated Western scholarship and influenced Arab scholars,and still does, though these were not the only possible choices. Modern scholars such as Fred Donner, Hugh Kennedy, and the Byzantinist Walter Kaegi (and many others) have challenged some of the conventional account and elaborated upon it.
There is an exception. Most of these modern reworkings either stop before the conquest of Egypt, or generally follow the broad interpretation put forth by Butler between 1902 and 1914.
His major work, The Arab Conquest of Egypt and the Last Thirty Years of the Roman Dominion, appeared in 1902, the same year Butler received his Ph.D. (Google books version; various other formats at Internet Archive here.) (Let me add that while the full original edition is available digitally online for free, there is a 1978 Second Edition from Cambridge University Press which collects the book and its two sequels and adds an Introduction and extensive "Additional Bibliography" by P.M. Fraser to bring the state of research down to the 1970s.)
That the book is still of value may seem somewhat surprising, since Butler wrote it without access to some of the key sources. He had seen only parts of Ibn ‘Abd al-Hakam's Kitab Futuh Misr, the earliest and fullest Muslim work on the subject, and judged that it contained "a good deal romance mingled with history." While that may hold true for the section on the Maghreb and Spain, Ibn ‘Abd al-Hakam came from a long line of Egyptian mutahddithun and thus was in possession of solid traditions dating from long before his own ninth century. Butler also lacked a full text of Tabari's massive universal history..
He did recognize that the Christian sources were much earlier than the Muslims', and made full use of the Chronicle of John of Nikiu, who wrote in the late seventh century and my have been a boy at the time of the conquests. (John's Chronicle can be found online here.)
In the 1902 book, however, Butler made a blunder concerning the value of the other key early source, The History of the Patriarchs. Although seemingly aware of the work he was misled by the attribution to Sawirus (Severus) of Ashmunayn and referred to it as a 10th century work. In fact, Severus was merely the compiler of earlier biographies, and that of the Patriarch Benjamin at the time of the Conquest was written by one George the Archdeacon, who flourished in the late 7th century and may also have been a boy at the time of the Conquest; in any event, he would have been able to speak to eyewitnesses. The section of the History of Patriarchs dealing with the period can be found in Patrologia Orientalis Vol. I, fasc. 4 in Arabic and B.T.A. Evetts' English translation (Google Books version here; various formats from Internet Archive here; English text only here).
Despite missing some key sources, Butler was able to offer a chronology of the conquest which still stands, and to put forward an interpretation of the figure known in the Arabic sources as "al-Muqawqis," identified by Butler as the Chalcedonian Patriarch Cyrus. Both of these interpretations still largely stand, though there have always been dissenters on the identification of al-Muqawqis. Still, most scholars accept Butler's view as largely correct. (Al-Muqawqis may be a post for another day.)
As Fraser points out in the 1978 edition and Additional Bibliography, the earlier parts of Butler, on Late Byzantine Egypt and the Persian occupation, do not hold up as well due to new sources, and the discovery of administrative papyri from the early Islamic period also renders his account of administration outdated. But the basic conquest narrative still largely stands, especially if read with Butler's two subsequent monographs.
For in fact Butler soon gained access to the sources he had missed, and wrote two updates, now usually reprinted together with The Arab Conquest. These were his 1913 The Treaty of Misr in Tabari: An Essay in Historical Criticism (various formats at Internet Archive) and his 1914 Babylon of Egypt: A Study in the History of Old Cairo (various formats at Internet Archive). The three works together remain the essential starting point for any historical research on the conquest period.