The Order of Assassins was a branch of the Ismaili sect of Islam, founded by Hassan ibn Sabbah (The Old Man of the Mountain). In 1090, the hill fortress of Alamut was constructed by Hassan in central Persia, and several other forts were built in the hills of that country. Although they were heavily persecuted, pressure on other Muslim states from first the Crusaders and then the Mongols (along with the obligatory program of political assassination), saved the Assassins from destruction. The Assassins expanded into Syria, often cooperating with the Christians against local Muslim rulers. The Mongols pushed the Assassins out of Persia in 1256. The Order survived in Syria until 1272, when the Mamluk Sultan Baybars destroyed their last stronghold. (Footnotes to history) …
Hassan’s devoted followers were prepared to follow his orders unquestioningly, even when this would result in their own certain deaths. He frequently sent them on missions to kill hostile princes, the generals of armies sent to oppose him, and anyone else of whom he disapproved. His fanatical, highly-trained and highly-disciplined killers would blend with the enemy population disguished as merchants or soldiers, awaiting their opportunity. They would then sneak into their target’s encampment or palace, and dispatch him with their long daggers. They were known as Hashishin from their habit of smoking hashish, either to generate visions of paradise or to give themselves courage before their (usually fatal) missions. This is the origin of the English word “assassin”.