Cao Pi
Following the Shu Han defeat at the Battle of Xiaoting, the alliance between Cao Pi and Sun Quan was tested, because the protection the agreement held was no longer needed as the Shu forces reestablished their own relations with the Sun clan. After Sun Deng, the crown prince and eldest son of Sun Quan, was demanded by Cao Pi as hostage, Sun Quan's relations with Wei ultimately plummeted. However, Cao Pi was trying to sour diplomatic relations between the Liu clan and the Sun clan. In November 222, Sun Quan declared himself independent once again from Wei, and Cao Pi responded with force.