Assault on Masyaf

The Assault on Masyaf was an event in Syria during 1183 at the Assassin's stronghold of Masyaf.

Takeover
In 1183, unknown to the Assassins, a Templar agent infiltrated the Order. Eventually, because of his knowledge of the Assassins and Masyaf's castle, he was able to lead a Templar attack on the fortress.

Now revealed to be a traitor, the Templars were able to take control of the castle and take several hostages, one being Al Mualim, Grand Master of the Assassin Order.

Altaïr's arrival
With the castle taken, the battle still continued, as the Templars and Assassins were fighting in the village below the castle. Eventually, Assassin Altaïr Ibn-La'Ahad arrived at the village, finding it in chaos. Noticing one of his fellow Assassins outnumbered by two Templars, Altaïr charged from behind on horseback.

Slashing one Templar with his sword, Altaïr dismounted and dispatched the other solider with a throwing knife before he could kill. Altaïr helped an Assassin, who was injured in battle, over to a bench. Asking who he was, Altaïr merely replied he was the son of Umar. As he helped the Assassin onto the bench, Abbas Sofian arrived and told Altaïr that the castle was overwhelmed.

Altaïr asked of Al Mualim, and Abbas explained that he was inside when the Templars took over the castle. As Altaïr starred at the fight from afar, Abbas insisted that their forces fall back, believing they could do nothing to save Al Mualim. However, Altaïr, confident he could save Al Mualim and retake the castle alone, instructed Abbas to have the Assassins flank the Templars once the castle gates were closed and drive them into the canyon.

Abbas shouted that Altaïr could not save Al Mualim, however, Altaïr simply told Abbas to make no mistakes with the task he given him.

Saving Al Mualim
Nearing the castle gates, Altaïr was stopped by the Templar agent, claiming they would kill Al Mualim if he came any further towards the castle. Altaïr warned the traitor he would not leave the castle alive. The Templar agent merely said he was no traitor, for he could not betray those he "never truly loved". Altaïr snarled that Templar had been living a lie. As the gate closed preventing Altaïr entering, he took an alternative route. Using the cracks and dents in the stone wall to make his way up to the battlements, Altaïr steathily dispatched any Templars he encountered.

As the Templar agent was beginning to kill off the hostages in the courtyard below, Altaïr jumped off the battlements and assassinated the Templar with his Hidden Blade. As the Templar died, he claimed the Templars knew that humans were weak and petty. Though Altaïr countered that the Creed was evidence to the contraty. The Templar agent then died claiming he was "too wise" to believe such things. With the castle retaken and saving Al Mualim, Altaïr walked down the courtyard with his mentor.

Al Mualim asked why Altaïr offered the Templar a chance at salvation. Altaïr claimed no person should die without being shown kindness. Al Mualim admitted to Altaïr that watching him grow from a boy to a man gave him much sadness and pride. Al Mualim claimed Altaïr fit the role of his father perfectly. After saying his father was an Assassin above all else, Al Mualim asked Altaïr if he regretted the Assassin life he had since a child. Altaïr asked how he could regret the only life he has ever known. Al Mualim finally told Altaïr that the battle for Masyaf was not over.

Aftermath
The Masyaf castle was retaken by the Assassins and Altaïr was promoted to rank of Master Assassin.

Source
 
 * Assassin's Creed: Revelations