The invading force in this event broke the dikes and canals, flooding the defenders' camps and Chinese engineers used palm stumps and house foundations as projectiles.
One ruler in this conflict, when presented with demands to acknowledge his opponent's authority, replied with a scornful letter calling the other leader a "young man…drunk with a 10 day success", which included the capture of Alamut. The invading force in this event broke the dikes and canals, flooding the defenders' camps and Chinese engineers used palm stumps and house foundations as projectiles. Because al-Mutasim was a religious as well as political leader his blood was not visibly shed as he was sewn into a carpet and trampled. During this event the translation center Bayt al\- Hikma was destroyed and survivors said the Tigris ran black with ink and red with blood.  For ten points, identify this 1258 event that involved the capture and sacking of Abbasid caliphate capital by Hulagu Khan and the Ilkhanate.
One ruler in this conflict, when presented with demands to acknowledge his opponent's authority, replied with a scornful letter calling the other leader a "young man…drunk with a 10 day success", which included the capture of Alamut.
Siege of Baghdad [accept answers that mention Baghdad and synonyms of destruction]