 He then intentionally allowed spies sent by Niu's superior Duan Chen (段琛) to steal the forgeries, causing Duan to suspect Niu's loyalty and begin to refuse to follow Niu's suggestions.Once Wei was sure of the dissension within the Eastern Wei forces, he made a surprise attack and captured both Duan and Niu, taking the locale for Western Wei.In 539, Emperor Wen promoted Wei's title from baron to marquess.