Circumstances were now particularly favourable to the plans of Hassan Sabah. On the death of sultan Malek Shah a civil war broke out among his sons for the succession. All the military chiefs and persons of eminence were engaged on one side or the other, and none had leisure or inclination to attend to the progress of the Ismaïlites. These, therefore, went on gradually extending their power, and fortress after fortress fell into their hands. In the course of ten years they saw themselves masters of the principal hill-forts of Persian Irak; they held that of Shahdorr[27] (_King's pearl_), and two other fortresses, close to Isfahan; that of Khalankhan, on the borders of Fars and Kuhistan; Damaghan, Kirdkoo, and Firoozkoo, in the district of Komis; and Lamseer and several others in Kuhistan. It was in vain that the most distinguished imams and doctors of the law issued their _fetuas_ against the sect of the Ismaïlites, and condemned them to future perdition; in vain they called on the orthodox to employ the sword of justice in freeing the earth from this godless and abominable race. The sect, strong in its secret bond of unity and determination of purpose, went on and prospered; the dagger avenged the fate of those who perished by the sword, and, as the Orientalized European historian of the society expresses it[28], "heads fell like an abundant harvest beneath the twofold sickle of the sword of justice and the dagger of murder." [Footnote 27: This castle was built by sultan Malek Shah. The following was its origin:--As Malek Shah, who was a great lover of the chase, was out one day a hunting, one of the hounds went astray on the nearly inaccessible rock on which the castle was afterwards erected. The ambassador of the Byzantine emperor, who was of the party, observed to the sultan, that in his master's dominions so advantageous a situation would not be left unoccupied, but would long since have been crowned with a castle. The sultan followed the ambassador's advice, and erected the castle of the King's Pearl on this lofty rock. When the castle fell into the hands of the Ismaïlites, pious Moslems remarked that it could not have better luck, since its site had been pointed out by a dog (an unclean beast in their eyes), and its erection advised by an infidel.] [Footnote 28: Hammer, 97.]