Xu Shu was a very modest man and is remembered for his filial devotion. When he was young, he killed a man to revenge his friend. Then he was rescued by his friends from prison, and he changed his name as Shan Fu. His scholarly endeavors include traveling as a student of Sima Hui and his association with Zhuge Liang. By and by he joined up with Liu Biao and was dispatched to serve under Liu Bei. He was Liu Bei's first brilliant strategist and he worked as his chief of staff.
     When Lu Kuang and Lu Xiang came assailing from Wei, Xu Shu helped trap and kill them in an ambush. Cao Ren was so infuriated at the loss of his men that he ignored Li Dian's warning and renewed his attack. Even the Eight Gates formation (eight paths lead to the enemy, each representing a different fate) could not trick Xu Shu. By nightfall, he raided and captured Fancheng, which Liu Bei established as his base. Cao Cao was surprised by his crafty plans and wanted Xu Shu to join him. Cheng Yu, who knew Xu Shu from the past, suggested a plan to bring Xu Shu over to Cao Cao which involved Xu Shu's mother. According to the plan, Cao Cao resorted to this tactic: he kidnapped Xu Shu's mother and forced Xu Shu to leave Liu Bei. Liu Bei felt it was only his duty to let Xu Shu go to her rescue, but Cao Cao only meant to capture him. Before he left, Xu Shu recommended Zhuge Liang as an advisor to Liu Bei.
     Thereafter he served Wei but he never gave any advices nor command any battles, since he was grievely sad over his mother's death and his true loyalty was with Liu Bei. Later in the Battle of Red Wall, Xu Shu saw through plans designed to overthrow Cao Cao, such as Huang Gai's feigned desertion and Pang Tong's chain-link scheme. As he was still loyal to Liu Bei, he did not alert Cao Cao, but he felt compelled to save his soldiers. With three legions of soldiers, Xu Shu set out to defend other territory that he said was under attack.
     When Zhuge Liang heard that Xu Shu was not being put to use within Cao Cao's troops, he remarked with regret, "Many men of talent are idle in Wei."