Templar attack on Masyaf

By 1189, Al Mualim—also secretly conspiring with the Assassins' sworn enemies, the Knights Templar—was covertly planning to retrieve a "Piece of Eden", an artifact from the First Civilization. This rumor caught the attention of the Templar Haras, who had gone undercover in the Assassin Order beforehand. Successful in capturing the Masyaf fortress, Al Mualim, and several other Assassins, Haras intended to retrieve information on the artifact from Al Mualim. Altaïr Ibn-La'Ahad, son of the late Umar, rode into Masyaf during the attack, and subsequently ordered Abbas Sofian—his former friend who had become his bitter rival—to flank the Crusader forces in the village and drive them into the canyon, while Altaïr himself went deeper into Masyaf, aiming to rescue Al Mualim. Locked outside the castle by Haras, Altaïr scaled the fortress walls and made his way towards the traitor, air assassinating him and saving Al Mualim in the process. This event led to Altaïr being elevated to Master Assassin, just as his father was. This also resulted in Altaïr's eventual arrogance and disregard of the Assassin's Creed, which further fueled Abbas Sofian's hatred towards him.