In 622 Mahomet founded Islamism; and some years after his death, in 638, the second of the khalifs, his successors, Omar, sent two of his generals, Khaled and Abou-Obeidah, to take Jerusalem.

For to the Mussulmans, also, Jerusalem was a holy city.

Mahomet, it was said, had been thither; it was thence, indeed, that he had started on his nocturnal ascent to heaven.

On approaching the walls, the Arabs repeated these words from the Koran: "Enter we the holy land which God hath promised us." The siege lasted four months.

The Christians at last surrendered, but only to Omar in person, who came from Medina to receive their submission.