In 1936 units under Wang's command were sent to reinforce the Inner Mongolian province of Suiyuan, which Yan controlled. Wang's orders were to defend against an attack by the Japanese puppet army of Mengguguo, led by Prince Teh (Demchugdongrub). Wang's senior commander in defending Suiyuan was Fu Zuoyi, who was also an officer of Yan's. In the subsequent battle with Mengguguo, Prince Teh's forces were virtually annihilated, and Prince Teh lost all areas in Suiyuan and Chahar which were not under the immediate protection of the Japanese Kwantung Army.