Play the Battle Of Fan Castle with the Wu forces on the hard difficulty setting. Make Mi Fang and Fu Shi Ren surrender. Then, go to the gate where it says that the reinforcements cannot come because of the guard captain there. Kill the guard captain and in a minute Xu Huang will arrive. When Zhang Fei and his sub-officer arrives, kill them both. If Xu Huang, Mi Fang, and Fu Shi Ren lived, you will get White Tiger.