In the expedition against Mecca a militant attitude was the inevitable result of compelling circumstances. The Meccans were actively hostile and had adopted a persecuting attitude towards those who accepted the new religion. At the time the Quraysh tribe, to which Muhammad belonged, was so far in the ascendant that its adhesion was necessary for the progress of Islam in the Hijaz: the championship of some prominent tribe was essential, and Muhammad himself was deeply attached to the traditional “House of God” at Mecca, to which his own family was bound by many associations; besides he desired the adherence of his own tribe as his mission was to it in the first place. Had the Meccan opposition not been broken down the Muslim religion could have been no more than the local cult of Madina, and even as such would have had to be perpetually on the defensive. No doubt the “holy war” as an institution was based on the traditions of this expedition, but such a war is related to the later enterprises for the conquest of non-Arab nations by a line of development which the Prophet himself could hardly have anticipated. The challenge to Heraclius is on a similar footing. Although we may not be disposed to accept the traditional account given by Bukhari, there no doubt was some such challenge. But Heraclius had only recently re-conquered Syria for the Byzantine Empire, the land he had acquired included a considerable portion of the Syrian desert which formed a geographical unity with Arabia, and amongst his subjects were Arab tribes closely akin to those of the Hijaz.