Haroun Al-Rashid (Aaron the Just), fifth caliph of the dynasty of the Abbassides, born in Rei about A. D. 765, died in Tus early in the spring of S09. He was the grandson of Abu Jaffar, surnamed Al-Mansour, and the son of the caliph Mahdi by the slave Khaizeran. In the reign of his father he led an army of 95,000 Persians and Arabs against the Byzantine empire, then ruled by Irene. He traversed Asia Minor, defeated the Greek general Nicetas, penetrated to the Bosporus (781), encamped on the heights of Chrysopolis (now Scutari), opposite Constantinople, and forced the empress to engage to pay an annual tribute of 70,000 dinas of gold, and to prepare the roads for his return to the Tigris. In 786 he succeeded his elder brother Hadi, who had vainly attempted to exclude him from the throne, and had even given orders for his execution, which was only prevented by his own sudden death. By his conquests and vigorous internal administration Haroun raised the caliphate to its greatest splendor, and made his reign esteemed the golden era of the Mohammedan nations.

His favorite ministers were Yahya and his son Jaffar, of the ancient Persian family of the Barmecides, whose ancestors had for many generations been hereditary priests at the fire temple of Balkh, and who now rapidly exalted the family to the highest dignities under the caliphate. While Haroun was occupied in fortifying the frontier provinces against the Greeks, Musa the Barmecide captured the chiefs of two hostile factions in Syria, brought them to Bagdad, and ended their dissensions; Fadhl, son of Yahya, conquered Cabool and pacified a rebellion in Dailem; and Jaffar joined to the office of vizier that of governor of Syria and Egypt. The whole internal administration of the empire fell into the hands of the Barmecides. They adorned the court with luxury, patron-ized letters and science, gave festivals, and made a prodigal use of the riches which they amassed. The reign of Haroun is chiefly sullied by the sudden disgrace which he inflicted on them in 803, condemning those from whose talents and services he had most profited to imprisonment or death. (See Barmecides.) He had devastated the Byzantine territories as often as Irene had declined payment of the annual tribute. In 803 her successor Nicephorus demanded restitution of all the sums the empress had paid.

The caliph replied : " In the name of the most merciful God, Haroun al-Rashid, commander of the faithful, to Nicephorus, the Roman dog. I have read thy letter, O thou son of an unbelieving mother. Thou shalt not hear, thou shalt behold, my reply." He immediately traversed and ravaged a part of Asia Minor, laid siege to Heraclea, brought Nicephorus to acknowledge himself a tributary, and retired triumphant to his favorite palace of Racca on the Euphrates. The peace being violated in 806, he returned rapidly in the depth of winter, and at the head of 135,000 men defeated Nicephorus in Phrygia, in a battle in which the Greek emperor was three times wounded and 40,000 of his subjects were slain. Again the tribute was refused, and Haroun returned in 808 with 300,000 men, desolated Asia Minor beyond Tyana and An-cyra, demolished Heraclea, devastated the islands of Rhodes, Cyprus, and Crete, and imposed a humiliating treaty on Nicephorus. It was soon broken, and Haroun again returned, took Sebaste, and swore never again to make peace with so perfidious an enemy. A revolt breaking out in Khorasan, the caliph died while on his march thither. In his latter years he corresponded with Charlemagne, and in 807 he sent him a tent, a clepsydra, an elephant, and the keys of the holy sepulchre.

He performed the pilgrimage to Mecca nine times, cultivated poetry and the arts and sciences, protected many illustrious scholars, and is the principal hero of the Arabian tales. He selected ministers under whose wise administration prosperous towns sprang up, commerce flourished, and Bagdad was enlarged and adorned and made the centre of Arabic civilization.