MOHAMMEDAN CAMPAIGNS. Among the military cataclysms which have changed the course of world-history on the largest scale, none is so little known to us in detail as the outburst of the first Mohammedan invaders from their Arabian deserts. That they smashed in a few years the old Sassanian kingdom of Persia, tore Syria, Egypt and Africa from the East Roman Empire, and even after their first wild rush was over, pushed their conquests as far as India on one flank and Spain on the other, is certain. But the details are wrapped in obscurity, and the very dates of important battles .and sieges are doubtful. This comes from the fact that we have no solid contemporary history written by the witnesses of the cataclysm. From the side of the conquerors there is nothing earlier than the chronicle of Al-Wakidi, written a full century after the Arab conquest of Syria and Persia, when the early campaigns of the Muslim had become a heroic legend, and were decorated with exploits and mar vels which make them not much more utilizable as solid history than the Chanson de Roland or the Romance of Fulk Fitzwarren. The Persian kingdom left memories of Sapor and Chosroes, mixed up with those of earlier and more fabulous kings, in much later epics—but no serious account of its own downfall. At Constan tinople the later 7th century and the earlier 8th century show the biggest blanks in chronicle-writing in the whole history of the East Roman realm. We have to depend for our knowledge of the Saracen invasion, as seen by the Christian witnesses, on Theo phanes and Nicephorus, both of whom wrote at the beginning of the 9th century, some 13o years or more after the loss of Syria and Egypt. They had no great desire to linger over the details of ancient disasters, nor had they any military interests. All that we get from them is curt mentions of battles and sieges, which are not always easy to identify with the military operations described by the romantic Al-Wakidi.
Matters become quite different as regards information when we have passed the year 800 : the series of contemporary Arab Chronicles begins and military details of value can be extracted from them of the organization of the armies of the 9th century Caliphs. Still more useful are the elaborate descriptions of Arab warfare in the Tactica of the Emperor Leo the Wise (886-912), the notes on the Byzantine Empire of his son Constantine Por phyrogenitus (912-959) and the Manual on Military operation of Nicephorus Phocas (963-969), all of which deal at length with the ways of the chief enemies of the empire.
Unfortunately the main military problem of the epoch is not how the armies of the Caliphs fought indecisively with those of the Emperors from A.D. 800 to i000, but how the first rush of Mohammed's earliest followers, a century and a half earlier, broke down the Roman Eastern frontier, which had stood suc cessfully for 600 years against enemies much more formidable, the Parthian and the Persian monarchies. On this neither the jejune annals of Theophanes and Nicephorus, nor the miraculous tales of Al-Wakidi and Al-Beladhuri give us any real assistance. We can only be certain that the destruction was not wrought either by heroic single combats, such as those which the Arab annalists describe, nor by the miracles of sand-storm and tempest with which they sometimes diversify their narratives. As far as we can reconstruct any outline of the campaigns of 632-641, the situation would seem to have been as follows. The old Roman military line of defence against the East had never been properly restored since the disasters of the reign of Phocas ; and the gar rison-armies of Syria and Mesopotamia had never been reconsti tuted on their old scale. When Heraclius imposed peace on the vanquished Persians in 629, he got back the Eastern provinces in a state of complete dilapidation—they had been in the hands of the enemy for more than ten years. The empire was bankrupt, and the army with which the last victories over the Persians had been won was an extemporized and heterogeneous levy, largely composed of barbarian auxiliaries. A great part of it must have been disbanded at the peace, for financial reasons. The recovered provinces had not settled down again to the habit of obedience; their population had been serving an alien master for many years, they had never been strong in "Roman" sentiment, and they were torn by virulent religious quarrels between the "orthodox" and the many sectarians. That active or passive dislike for the restored imperial government was rife is shown by the tame sub mission of many sections to the next invader, and by the not in frequent cases of actual treachery. The first Roman fortress which' the Arabs attacked—Bostra—was surrendered by an apos tate governor.