for indoctrination of his followers. After laying claim to the fortress at Alamut, Sabbah began expanding his influence outwards to nearby towns and districts, using his agents to gain political favour and to intimidate the local populations. Spending most of his days at Alamut producing religious works and developing doctrines for his order, Sabbah would never again leave his fortress. Murder for religious purposes was not new to the region, as the strangler sects of southern Iraq dating to the eighth century have shown. The strangler sects were stopped by the Umayyads; the Assassins would not be by the later caliphates. Shortly after establishing their headquarters at Alamut Castle, the sect captured Lambsar Castle, to be the largest of the Isma'ili fortresses and confirming the Assassins' power in northern Persia. The estimated date of the capture of Lambsar varies between 1096 and 1102. The castle was taken under the command of Kiya Buzurg Ummid, later Sabbah's successor, who remained commandant of the fortress for twenty years. No interactions between the Christian forces of the First Crusade and the Assassins have been noted, with the latter concentrating on the Muslim enemies of the former. Other than a mention of Tancred's 1106 taking of Apamea (see below) in Gesta Tancredi, Western Europe likely first learned of the Assassins from the chronicles of William of Tyre, A History of Deeds Done Beyond the Sea, published much later. William coined the phrase "Old Man of the Mountain" to describe the Nizari Isma'ili da'i at Alamut. The Assassins were immediately threatened by the forces of Seljuk sultan Malik-Shah I, marking the beginning of the Nizari-Seljuk wars. One of Sabbah's disciples named Dihdar Bu-Ali from Qazvin rallied local supporters to deflect the Seljuks. Their attack on Alamut Castle and surrounding areas was canceled upon the death of the sultan. The new sultan Barkiyaruq, son of Malik-Shah I, did not continue the direct attack on Alamut, concentrating on securing his position against rivals, including his half-brother Muhammad I Tapar, who eventually settled for a smaller role, becoming malik (translated as "king") in Armenia and Azerbaijan. The first notable assassination was that of powerful Seljuk vizier Nizam al-Mulk in 1092, who had helped propel Barkiyaruq to lead the sultanate. Sabbah is reputed to have remarked, "the killing of this devil is the beginning of bliss" on hearing to the death of Nizam. Of the 50 assassinations conducted during