It was when the Roman Emperor Constantine embraced Christianity, and his
mother Helena discovered the true Cross and the Holy Places, that
Jerusalem came again into prominence. Thereafter, churches and
monasteries sprung up throughout Palestine, which thus, for a time,
became thoroughly Christianized, under the Christian Emperors of Rome
and Byzantium. But the seventh century saw the fall of the Christian
ascendancy in Syria. In A.D. 614, the Persians, under Chosroes, swept
through the land, massacring the Christians wholesale, and destroying
most of their churches, including the Church of the Holy Sepulchre. The
withdrawal of the Persians was followed by a brief return of Christian
ascendancy lasting but eight years, under the Emperor Heraclius. And
then, in 637, Jerusalem fell to the growing power of Islam. It was this
new religion, with a calendar only dating from A.D. 622, which was to
control the future destinies of the Holy City.

Islam arose at Mecca and Medina in barren and uninviting Arabia. When it
started on that expansion, whereby it overspread half of the known
world, Syria, from its situation, was naturally the first country to
tempt its restless and devoted Arab warriors. Within ten years of the
Hegira, or commencement of the Mahomedan era, we find the followers of
the Prophet already in Syria. The Byzantine army was overwhelmed at the
battle of the Yarmuk, and the Arabs laid siege to Jerusalem. The city
capitulated to Omar, who granted terms of comparative magnanimity. His
terms gave to the Christians security of person and property, safety of
their churches, and non-interference on the part of Mahomedans with
their religious exercises, houses or institutions. Upon the site of the
Temple, which had been systematically defiled by the Christians out of
abhorrence for the Jews, but which was honoured by the Moslems as the
spot from which Mahomed ascended to heaven, was now erected the Mosque
of Omar. This site became to the Mussulman, the most venerated spot in
Jerusalem, as was the Church of the Holy Sepulchre to the Christian.
When, in after years, pilgrimages to Mecca were temporarily interrupted,
devout Mahomedans made the pilgrimage to Jerusalem instead.

For the next few centuries Christian and Muslim lived together upon a
fairly workable basis of toleration. Massacres of Christians and
destruction of their churches occurred periodically, either in revenge
for Christian successes elsewhere, or in c