Hanzhong Campaign
In 219, when Cao Cao's general Cao Ren was being besieged at Fancheng (樊城; present-day Fancheng District, Xiangyang, Hubei) by Liu Bei's general Guan Yu, Cao Cao was away at the Hanzhong Campaign so he ordered his generals to lead troops from their respective garrisons to reinforce Cao Ren.