Let us turn for a moment to the antecedents of the Arab invaders. History affords no parallel, whether from a religious or political point of view, to the sudden rise of Mohammedanism and the wonderful conquests which it made. "The electric spark[2] had indeed fallen on what seemed black unnoticeable sand, and lo the sand proved explosive powder and blazed heaven-high from Delhi to Granada!" Mohammed began his preaching in 609, and confined himself to persuasion till 622, the year of the Flight from Mecca. After this a change seems to have come over his conduct, if not over his character, and the Prophet, foregoing the peaceful and more glorious mission of a Heaven-sent messenger, appealed to the human arbitrament of the sword: not with any very marked success, however, the victory of Bedr in 624 being counterbalanced by the defeat of Ohud in in the following year. In 631, Arabia being mostly pacified, the first expedition beyond its boundaries was undertaken under Mohammed's own leadership, but this abortive attempt gave no indications of the astonishing successes to be achieved in the near future. Mohammed himself died in the following year, yet, in spite of this and the consequent revolt of almost all Arabia, within two years Syria was overrun and Damascus taken. Persia, which had contended for centuries on equal terms with Rome, was overthrown in a single campaign. In 637 Jerusalem fell, and the sacred soil of Palestine passed under the yoke of the Saracens. Within three years Alexandria and the rich valley of the Nile were the prize of Amru and his army. The conquest of Egypt only formed the stepping-stone to the reduction of Africa, and the victorious Moslems did not pause in their career until they reached the Atlantic Ocean, and Akbah,[3] riding his horse into the sea, sighed for more worlds to conquer. We may be excused perhaps for thinking that it had been well for the inhabitants of the New World, if Fortune had delivered them into the hands of the generous Arabs rather than to the cruel soldiery of Cortes and Pizarro. [1] Al Makk., ii. 34. "What are thirty barbarians perched upon a rock? They must inevitably die." [2] Carlyle's "Hero Worship" ad finem. [3] Cardonne, i. p. 37; Gibbon, vi. 348, note. In 688, that is, in a little more than a generation from the death of Mohammed, the Moslems undertook the siege of Constantinople. Fortunately for the cause of civilisation and of Christendom, this long siege of several years proved unsuccessful, as well as a second attack in 717. But by the latter date the footing in Europe, which the valour of the Byzantines denied them, had already been gained by the expedition into Spain under Tarik in 711. The same year that witnessed the crossing of the Straits of Gibraltar in the West saw also in the East the passage of the Oxus by the eager warriors of Islam.