As the Ngô Quyền march his forces to Đại La, Kiều Công Tiễn sent the envoys to Southern Han to petition for sending army to help himself. Emperor of Southern Han, Liu Yan, commissioned his son, Liu Hongcao to help Kiều Công Tiễn, he also led another army to supply his son. But Công Tiễn was executed before this army arrived. In the November 938, at the Battle of Bạch Đằng, the fleet was defeated by Ngô Quyền, Liu Hongcao was killed in battle. Dương Tam Kha participated in this battle.