[The turning point of Li Shih-min’s campaign in 621 A.D. against the two rebels, Tou Chien-te, King of Hsia, and Wang Shih-ch’ung, Prince of Cheng, was his seizure of the heights of Wu-lao, in spite of which Tou Chien-te persisted in his attempt to relieve his ally in Lo-yang, was defeated and taken prisoner. See _Chiu T’ang Shu_, ch. 2, fol. 5 verso, and also ch. 54.]