Five years after this expedition, Harun ascended the throne of his father and his elder brother; the most powerful and vigorous monarch of his race, illustrious in the West, as the ally of Charlemagne, and familiar to the most childish readers, as the perpetual hero of the Arabian tales.

His title to the name of _Al Rashid_ (the _Just_) is sullied by the extirpation of the generous, perhaps the innocent, Barmecides; yet he could listen to the complaint of a poor widow who had been pillaged by his troops, and who dared, in a passage of the Koran, to threaten the inattentive despot with the judgment of God and posterity.

His court was adorned with luxury and science; but, in a reign of three-and-twenty years, Harun repeatedly visited his provinces from Chorasan to Egypt; nine times he performed the pilgrimage of Mecca; eight times he invaded the territories of the Romans; and as often as they declined the payment of the tribute, they were taught to feel that a month of depredation was more costly than a year of submission.

But when the unnatural mother of Constantine was deposed and banished, her successor, Nicephorus, resolved to obliterate this badge of servitude and disgrace.

The epistle of the emperor to the caliph was pointed with an allusion to the game of chess, which had already spread from Persia to Greece.