Excepting raids of little import, Syria had for some time past enjoyed rest,[442] when suddenly in the second year of this Caliphate, Muâvia was startled by the approach of an army from Asia Minor, which he had not the means to oppose. Othmân ordered troops to pass over from the eastern provinces, and eight thousand volunteers soon joined the Syrian army. Thus reinforced, the Arabs repulsed the Byzantine attack. Following up their success, they overran Asia Minor, and, piercing the heart of Armenia, joined their comrades on the Persian border within sight of the Caspian. Thence they penetrated as far north as Tiflis, and even to the shores of the Black Sea. Thereafter hostilities were renewed for a long period every summer; and eventually, aided by naval expeditions from the ports of Africa, the Syrian generals pushed forward their conquests in the Levant and Asia Minor, enlarged their coasts, and strengthened their border. [Sidenote: _Africa._ A.H. XXV. A.D. 646.] In Africa, I have already noticed the desperate attack made early in the reign of Othmân on Alexandria from seaward. The Byzantine forces, for a little while, regained possession of the city, but (as we have before related) were finally driven out by Amru; and against the Moslem power in Egypt no further attack was made. The Imperial arms, however, were still active in Africa; and along the northern shores of the Mediterranean, strong Arab columns were long actively engaged. Among the chiefs who had joined the Egyptian army was Abu Sarh,[443] already noticed as the foster-brother of Othmân. He did not bear an enviable reputation in Islam; for having been employed by Mahomet as amanuensis to record his early revelations, he had proved in some way unfaithful to the trust; and on the capture of Mecca, was in consequence proscribed from the amnesty, and only at the intercession of Othmân escaped being put to death. [Sidenote: Abu Sarh supersedes Amru in Upper Egypt. A.H. XXVI. A.D. 647.] Possessed of administrative ability, he had been appointed by Omar to the government of Upper Egypt. But some years after, he fell out with Amru, in whom was vested the supreme control of the province; and each appealed to Othmân. Amru was declared to be in fault, and the Caliph deposed him altogether from the civil charge of Egypt. Amru objected. ‘To be over the army,’ he said, ‘and not over the revenue, was but holding the cow’s horns, while another milked her.’ He repaired angrily to Othmân, who, after some words of bitter altercation, transferred the entire administration, civil and military, into the hands of Abu Sarh. The act was unfortunate for the Caliph. It threw Amru into the ranks of the disaffected party at Medîna; while the bad repute of ‘the renegade’ Abu Sarh, though he was an able warrior, gave point to the charges of partiality and nepotism now rife against Othmân.[444] [Sidenote: Conquest in Northern Africa. A.H. XXVI. A.D. 647.]