[Sidenote: Sád establishes his head-quarters at Medâin.] As Medâin offered every convenience for the seat of government, Sád established his head-quarters there. The palaces and mansions of the fugitive nobles were divided amongst his followers. The royal residence he occupied himself. The grand hall, its garnishing unchanged, was consecrated to Divine worship, and here, as a cathedral service, the Friday ritual was first celebrated in Irâc. CHAPTER XVIII. BATTLE OF JALOLA--REDUCTION OF MESOPOTAMIA--KUFA AND BUSSORA FOUNDED. A.H. XVI. A.D. 637. [Sidenote: Battle of Jalôla.] OMAR was satisfied, as well he might be, with the success achieved. His old spirit of caution revived, and, beyond rendering Mesopotamia and the border-lands within the Persian mountain range secure, he strictly forbade any forward movement. The summer of the sixteenth year of the Hegira was, therefore, passed by Sád in repose at Medâin. The king, with his broken troops, had fled into the mountains, and thence into the plains of Persia. And the people on either bank of the Tigris, seeing opposition vain, readily submitted themselves to the conqueror. In the autumn, however, the Persians, resolving again to try the chance of arms, flocked in great numbers to Yezdegird, and an army was formed at Holwân, a fortress on the stream of that name a hundred miles north of Medâin. From thence Mehrân, with part of the force, advanced to Jalôla, a stronghold on the mountain range half-way to Medâin. [Sidenote: Persians advance. A.H. XVI. Autumn, A.D. 637.]This place, capable of accommodating an army, and almost impregnable to such an enemy as the Moslems, was defended by a deep trench, and all outlets or accessible places guarded by _chevaux de frise_ and spikes of iron. The movement was reported to the Caliph, and, with his sanction, Sád pushed forward Hâshim and Cacâa at the head of 12,000 men, including the flower of Mecca and Medîna; and they sat down in front of the citadel. The garrison, reinforced from time to time by the army at Holwân, made an obstinate defence, and in frequent sallies attacked the besiegers with desperate bravery. Fresh troops had to be despatched from Medâin, and the siege was prolonged for eighty days. At length, on the occasion of a vigorous sally, a great storm darkened the air; and the Persian columns, losing their way, were pursued to the battlements by Cacâa, who seized one of the gates. Driven thus to desperation, they turned upon the Arabs, and a general engagement ensued, which ‘was not surpassed by the _Night of Clangour_, excepting that it was shorter.’ [Sidenote: The Persians routed, and Jalôla taken. Dzul Cáda, A.H. XVI. December, A.D. 637.]Beaten at every point, many of the enemy in the attempt to flee were caught by the iron spikes. They were pursued to some distance,[297] and the fields and roads were strewn (tradition