 In 1248 , a Crusader fleet of 1 @,@ 800 boats and ships arrived in Cyprus with the intent of launching a Seventh Crusade against the Muslims by conquering Egypt . Their commander , Louis IX , attempted to enlist the Mongols to launch a coordinated attack on Egypt , but when this failed to materialize , the Crusader force sailed to Damietta and the local population there fled as soon as they landed . When as @-@ Salih Ayyub , who was in Syria at the time , heard of this , he rushed back to Egypt , avoiding Damietta , instead reaching Mansurah . There , he organized an army and raised a commando force which harassed the Crusaders . 
