Thus political demoralization, impelled both by internal discord and foreign interference, went steadily on. National unity was unknown to the Arabs, with whom the largest measure of personal liberty was the rule of public as well as of private life. That principle of cohesion which binds communities together by the ties of common interest was not recognized in a society where each man considered he had an inalienable right, based upon immemorial prescription and the traditions of the Desert, to plunder his neighbor. Even the greatest of the Ommeyade khalifs were hated by the people. Their lives were never safe. Their persons were constantly guarded by armed foreigners,--Christian Mamelukes, Berber mercenaries, African eunuchs. Fear alone maintained their authority. Their subjects were ignorant of loyalty, patriotism, public spirit, or national honor. The victories of these princes might dazzle the populace. Their liberality might for the moment secure the attachment of the army. The erection of magnificent houses of worship might elicit the applause of the devout; but the possession of the most noble qualities availed nothing in the hour of disaster. The prestige of a distinguished name, the memory of splendid exploits, the sight of grand architectural monuments, the omnipresent culture of a great people, were trifles in the eyes of the Arab bent on blood-revenge, or of the Berber savage with the prospect of the booty of a palace like that of the Medina-al-Zahrâ before him. The rottenness of the Moslem system was disclosed by the death of Al-Mansur. He was the most illustrious captain who ever led the armies of Islam to battle. He was the greatest potentate in Europe. In a quarter of a century of constant warfare no reverses had ever diminished his popularity or tarnished his renown. To all appearances, his power, nominally the power of the khalifate, was established upon an enduring and impregnable basis. Yet he was hardly in his grave before the imposing fabric of the Moorish empire crumbled into dust, and with it disappeared forever the grandeur, the glory, and the civilization of three hundred eventful years. CHAPTER XVII WARS WITH THE CHRISTIANS, THE ALMORAVIDES 1044–1121