In late September or October 249, Linghu Yu sent his subordinate Zhang Shi (張式) to contact Cao Biao and tell him that there were two popular sayings circulating in Dong Commandery (東郡; around present-day Puyang County, Henan): "A magical horse emerges from the White Horse River.
The following day, its tracks are seen to be as large as one hu and stretching over some li before leading back to the river.
Zhang Shi also told Cao Biao, "His Excellency (Linghu Yu) sends Your Highness his greetings.
[11][12][13] On 7 June 251, the Wei imperial court received news that Wang Ling was plotting a rebellion in Shouchun (壽春; present-day Shou County, Anhui) aimed at overthrowing the emperor Cao Fang and replacing him with Cao Biao.
The Grand Tutor Sima Yi then led imperial forces from Luoyang to Shouchun to preempt Wang Ling before he could effectively carry out his plans.
[14] As Wang Ling did not expect Sima Yi to show up so quickly, he was caught off guard and had no choice but to surrender.
[15] Sima Yi and officials from the Imperial Censorate went to Cao Biao's princedom, conducted an investigation and arrested everyone involved in the plot.
[16][17][18] Several of Cao Biao's subordinates, who knew of his involvement in the plot but did not report him, were implicated and executed along with their families.
[19] Cao Biao's family members were spared, but reduced to commoner status and relocated to Pingyuan Commandery (平原郡).