The order of the Knights of St. John, which for some centuries played a very important part in the great struggle between Christianity and Mahomedanism, was, at its origin, a semi-religious body, its members being, like other monks, bound by vows of obedience, chastity, and poverty, and pledged to minister to the wants of the pilgrims who flocked to the Holy Places, to receive them at their great Hospital—or guest house—at Jerusalem, dedicated to St. John the Baptist, and to defend them on their passage to and from the sea, against attack by Moslems.