 In 1164 , Nur al @-@ Din dispatched Shirkuh to lead an expeditionary force to prevent the Crusaders from establishing a strong presence in an increasingly anarchic Egypt . Shirkuh enlisted Ayyub 's son , Saladin , as an officer under his command . They successfully drove out <unk> , the vizier of Egypt , and reinstated his predecessor Shawar . After being reinstated , Shawar ordered Shirkuh to withdraw his forces from Egypt , but Shirkuh refused , claiming it was Nur al @-@ Din 's will that he remain . Over the course of several years , Shirkuh and Saladin defeated the combined forces of the Crusaders and Shawar 's troops , first at <unk> , then at a site near Giza , and in Alexandria , where Saladin would stay to protect while Shirkuh pursued Crusader forces in Lower Egypt . 
