Chen Shi was first mentioned in 217 when he participated in the Hanzhong Campaign under Liu Bei's command. Liu Bei sent him and ten other officers to lead their troops to cut off the enemy's route along the gallery roads at Maminge Path (馬鳴閣道; in present-day Guangyuan, Sichuan). However, they were driven back by Xu Huang, a general under Liu Bei's rival Cao Cao, and many of Liu Bei's soldiers fell off the gallery roads into the deep valleys and died during the attack.