nd that this
was the real cause of Harun's anger against the Barmecides (q.v.).
Dreading fresh insurrections of the Alids, Harun secured the person of
another descendant of Ali, Musa b. Ja'far, surnamed al-Kazim, who
enjoyed great consideration at Medina, and had already been arrested and
released again by Mahdi. The unfortunate man was brought by the caliph
himself to Bagdad, and there died, apparently by poison.

Meanwhile Harun did not forget the hereditary enemy of Islam. In the
first year of his reign all the strong places of Kinnesrin and
Mesopotamia were formed into a special province, which received the name
of al-'Awasim ("the defending fortresses"), with Manbij (Hierapolis) as
its capital. The building of the fortress of Hadath having been
completed, Harun committed to Faraj the Turk the task of rebuilding and
fortifying the city of Tarsus. Thanks to these and similar measures, the
Moslem armies were able to advance boldly into Asia Minor. Almost every
year successful raids were made, in the year 797 under the command of
the caliph himself, so that Irene was compelled to sue for peace. An
attack by the Khazars called the caliph's attention from his successes
in Asia Minor. This people had made an irruption into Armenia, and their
attack had been so sudden that the Moslems and Christians were unable to
defend themselves, and 100,000 had been reduced to captivity. Two
valiant generals, Khozaima b. Khazim and Yazid b. Mazyad, marched
against the Khazars and drove them out of Armenia.

In the midst of the cares of war, Harun was assiduous in his religious
duties, and few years passed without his making the pilgrimage. Having
determined to fix the order of succession in so formal a manner as to
take away all pretext for future contentions, he executed a deed by
which he appointed his eldest son Mahommed his immediate heir, and after
him the second, Abdallah, and after Abdallah the third, Qasim. Mahommed
received the surname of _al-Amin_ ("the Sure"), Abdallah that of
_al-Ma'mun_ ("he in whom men trust"), and Qasim that of _al-Mo'tamin
billah_ ("he who trusts in God"). Harun further stipulated that Mamun
should have as his share during the lifetime of his brother the
government of the eastern part of the empire. Each of the parties
concerned swore to observe faithfully every part of this deed, which the
caliph caused to be hung up in the Ka'ba, imagining that it would be
thus guaranteed against all violation on the