Cao Rui (simplified: 曹叡, traditional: 曹叡, pinyin: Cáo Ruì), posthumously Emperor Ming of Wei (魏明帝), was the second emperor of Cao Wei, reigning from 226 to 239. He was the son of Cao Pi and succeeded him at age twenty-two. His reign saw Zhuge Liang’s Northern Expeditions, which Wei resisted under Sima Yi and others; Cao Rui also moved the court to Luoyang and undertook large-scale building. He died in 239 and was succeeded by his adopted son Cao Fang.
Biography
Succession and early reign
Cao Rui was a son of Cao Pi and Lady Zhen. He was enfeoffed as Prince of Qi and then Prince of Pingyuan. When Cao Pi died in 226, Cao Rui ascended as emperor. He retained capable regents and generals, including Sima Yi, Cao Zhen, and Cao Xiu, to defend the borders and govern.
Northern Expeditions and defence
During his reign Zhuge Liang of Shu launched several Northern Expeditions. Cao Rui sent Sima Yi and other commanders to hold the passes; the Battle of Jieting (228) and subsequent campaigns were fought under his reign. He also sent Xin Pi with the imperial staff to restrain Sima Yi at Wuzhangyuan when Zhuge Liang challenged Wei to battle. Wei held its frontiers and did not yield major territory.
Luoyang and succession
Cao Rui moved the court to Luoyang and ordered construction of palaces and halls, which drew some criticism for expense. He had no surviving biological son; he adopted Cao Fang and on his deathbed entrusted him to Sima Yi and Cao Shuang. He died in 239 and was succeeded by Cao Fang.
Legacy
Cao Rui is remembered as a capable second emperor of Wei who maintained the realm against Shu’s Northern Expeditions and consolidated the capital at Luoyang. His choice of Cao Fang and the regency set the stage for the later rise of the Sima family.