 Complete the following phrase:  Nevertheless, al-Mutasims hold on the throne was still shaky, and he abandoned Mamuns campaign; the new base at Tyana was razed, and the still restive army returned to the Caliphate. Despite his acceptance of his uncles succession, Abbas was removed from his governorship of the frontier lands, but retained the support of several leading figures in the Abbasid court. He soon became the focus of the factions opposed to al-Mutasim, and in particular his increasing reliance on, and favour shown to, his Turkish slave-soldiers ghilman. This discontent resulted in an alleged conspiracy led by the general Ujayf ibn Anbasa which aimed to kill al-Mutasim and place Abbas on the throne. The plot was reportedly uncovered while al-Mutasim was campaigning against the Byzantines in 838, with the Caliph informed of it just after the celebrated 