Assassins

I was playing Assassins Creed earlier today and got to thinking about the effect hashshashins had during the time of the crusades and how they played into the scene. The hashshashin movement started around 1090 and continued until 1256. They fought under Hasan ibn Sabbah at the beginning with the belief that following him was the only way to receive salvation. They listening to him without question and ended up taking the lives of many nobles including Raymond II of Tripoli, Conrad de Montferrat, and Prince Edward. Sometime they even fought along with the Crusaders but only because they had similar enemies.
There's not much information I could find about how they specifically were involved... but I'd really love to find more information on this!!!
- Abby