OMAR, ADt-ITAFSA-TBN-AL-KTIETTAB. the second caliph of the Moslems, was h. about 581. His early history is little known, but previous to his conversion he was an ardent persecutor of Mohammed and his followers. After his conversion he became as zealous an apostle as he had formerly been a persecutor, and rendered valuable aid to the prophet in all his warlike expeditions. After Mohammed's death, he casused Abti-bekr to be proclaimed caliph, and was himself appointed haujeb, or prime-minister. Though of a fiery and enthusiastic temperament, he proved a sagacious adviser, and it was at his suggestion that the caliph put down with an iron hand the many dissensions which had arisen among the Arabs after the prophet's decease, and resolved to strengthen and con solidate their new-born national spirit, as well as propagate the doctrines of Islam, by engaging them in continual aggressive wars. On the death of Abu-bekr, Omar, sue ceeCleil as caliph, and pushed on the wars of conquest with increased vigor. He was sum moned to Jerusalem in 637, to receive the keys of that city, and before leaving gave orders to build a mosque. now called by his name, on the site of the temple of Solomon. Omar now took the command of a portion of the army, and reduced the other chief cities of Palestine. He then planned an invasion of Persia, which was commenced the same year, and by .642 the whole of what is•now 'known as Persia was subdued. In the meantime the war • in Sykia teas vigorously prosecuted, and the Byzantine armies, repeatedly defeated, at length gave up the contest. In 639, Antra, one of his generals, had invaded Egpyt with a considerable force; but such was the prestige of the Arabs, or the incapacity of the lieutenants of the emperor Heraclius. that this valuable country, with its six millions of people, was reduced under the caliph's authority without it single contest, and only two towns, Misr and Alexandria, were even attempted to be defended.
(For the story which was till lately believed concerning the destruction of the Alexandrian library, see ALEXANDRIAN LIBRARY.) Barca and Tripoli were next subdued by Antra. On the n., Armenia was overrun in 641, and the caliph's afithority now reached from the desert of Khiva to the Syrtis, an enormous extension in ten years. In 644 Omar was assassinated in the mosque of Median by a Persian slave from motives of revenge. Ile languished five days after receiving the wound, but refused to appoint a successor, and named six commissioners who were to choose one from themselves. He was buried in the mosque of Medina, near the prophet and Abu-bekr, and his tomb is still visited by pilgrims.
Omar may be called the founder of the Mohammedan power, as from a mere sect he raised it to the rank of a conquering nation, and left to his successor an empire which Alexander the great might have envied. In him we find a rare combination of qualities, the ardent zeal of the apostle side by side with the cautions foresight and calm resolution of the monarch. His great military talents, and severity to "obstinate unbelievers," rendered him formidable to his enemies, and hia inexorable justice rendered him no less obnoxious to the more powerful of his subjects, and gave rise to many attempts at his assassination. Omar was the founder of many excellent institution; he assigned a regu lar pay to his soldiers, established a night-police in towns, and made some excellent regulations for the more lenient treatment of slaves. He also originated the practice of dating from the era of the Iletyrah (q.v.). He assumed the title of Emir-al mumenin (" Commander of the Faithful") in preference to that of Kliatifah-raeouli-Ilahi. the ordi nary designation; and to the present day his name is held in the greatest veneration by the orthodox or Simi sect of Moslems.