High Quality Content by WIKIPEDIA articles! Yang Yi was a minister of the Three Kingdoms period in China's history. Yang Yi was originally a subject of Cao Wei and later defected to Guan Yu, who sent him to Liu Bei. Liu Bei liked Yang Yi very much after talking with him and kept him by naming him as Left General Commanding Officer, and after becoming an emperor, Liu Bei promoted Yang Yi as Imperial Secretary. While not a particularly spectacular general, Yang Yi inadvertently weakened the Shu Han by slaying the general Wei Yan due to a personal grudge. Yang Yi participated in the Northern Expeditions of Shu under the command of the strategist Zhuge Liang. He and Wei Yan did not get along well, and it was only the command of Zhuge Liang that kept them from fighting one another outright. When Zhuge Liang died during his final campaign against Cao Wei, Yang Yi and Wei Yan conflicted on whether to follow Zhuge's orders to retreat. Their disagreement finally broke out into a full-fledged battle, which Yang Yi eventually won. He also slew Wei Yan's entire family shortly after.