For Hulegu [Khan, grandson of Genghis], the ultimate prize was to conquer the Arab cultural and financial capital of Baghdad, but to get there, he had to reassert Mongol authority over several rebellious areas en route. The most difficult of these was to conquer the strongholds of the Nizari Ismailis, a heretical Muslim sect of Shiites more commonly known in the West as the Assassins. They were holed up in perhaps as many as a hundred unconquered mountain fortresses stretching from Afghanistan to Syria, the most important of which was Alamut, the Eagle's Nest, in northern Persia. Members followed without question the orders of their hereditary leader, who was known by many titles, such as Imam, the Grand Master, or Old Man of the Mountain. Because they believed that God chose the Imam, he was therefore infallible; he needed no education since everything he did, no matter how odd it might appear to mortals, was considered divinely inspired. His followers accepted seemingly irrational acts, frequent changes of the law, and even the reversal of the most sacred precepts as evidence of God's plan for humanity.SOURCE: Genghis Khan and the Remaking of the Modern World, by Jack Weatherford (Three Rivers Press, 2004), pp. 178-180
Despite the lack of a conventional army, the Ismaili sect exercised tremendous political power through a highly sophisticated system of terror and assassination, and the secrecy and success of the group bred many myths, making it, still today, difficult to factor out the truth. The cult apparently had one simple and effective political strategy: kill anyone, particularly leaders or powerful people, who opposed them in any way. The cult recruited young men who were willing to die in their attacks with the assurance that they would achieve instant entry into paradise as martyrs of Islam. The Chinese, Persian, and Arabic sources all relate the same account of how young men were lured by ample quantities of hashish and other earthly delights that awaited them in the special gardens of the cult's castles and fortresses. This was the foretaste of the paradise that awaited them if they died in the Grand Master's service. He then trained them and controlled them with a steady supply of hashish to keep them obedient and make them fearless. Supposedly, because of the importance of narcotics for the Ismailis, the people around them called them hashshashin, meaning "the hashish users." Over time, this name became modified into the word assassin. Whether the killers had actually used hashish to inspire them or not, the name spread into many languages as the word for the murderer of high officials.
Earlier, in the time of Genghis Khan's first invasion of the region, the Grand Master willingly swore obedience to the Mongols. In the following decades, the Assassins flourished in the power vacuum created by Genghis Khan's defeat of the Turkic sultan of Khwarizm and then the withdrawal of most of the Mongol forces. By the time Mongke Khan ascended the throne, the Assassins feared that the return of a large Mongol army might interfere with their newfound powers. In what may have been only a pretext for Hulegu's attacks, some chroniclers wrote that the Grand Master sent a delegation to Karakorum ostensibly to offer submission to Mongke Khan, but actually trained to kill him. The Mongols had turned them away and prevented the assassination, but because of it Mongke Khan decided to crush the sect permanently and tear down their fortresses.
Before Hulegu's army reached the Assassin strongholds, the drunken and debauched Grand Master was murdered by disgruntled members of his own entourage and replaced by his equally incapable son. Hulegu assessed the difficulty of capturing the heavily fortified castles one by one, and he devised a simple and more direct plan. Because of the sacred role of the Grand Master, Hulegu concentrated on capturing him with a combination of massive military might and the offer of clemency if he should surrender. The Mongols bombarded the Ismaili stronghold, and the Mongol warriors proved capable of scaling the steepest escarpments to surprise the defenders of the fortress. The combination of force, firepower, and the offer of mercy worked, and on November 19, 1256, on the first anniversary of his coming to power, the Imam surrendered to the Mongols.
Once Hulegu had control of the Imam, he paraded him from Ismaili castle to Ismaili castle to order his followers to surrender. To encourage the cooperation of the Imam and keep him happy until the end of the campaign, Hulegu indulged his [the Imam's] obsessive interest in watching camels fight and mate, and he supplied him with girls. In the spring of 1257, once the Assassins' castles had been taken, the Imam recognized his loss of usefulness to the Mongols, and he requested permission to travel to Karakorum to meet with the Great Khan Mongke himself, perhaps to work out some plan for his own survival. Hulegu sent him on the long journey to Mongolia, but once the Imam arrived there, Mongke refused to see him. Instead, the Mongol escort took the Imam and his party out to the mountains near Karakorum and stomped them to death.