According to some sources, Wu Sangui's army, when it was engaged with Li Zicheng's in the beginning stage of the Battle of Shanhai Pass, was being worn down and was on the verge of defeat before a sandstorm blew in and the Qing army attacked during the confusion. What if by some circumstance, perhaps an earlier engagement of the two armies, Wu Sangui's line broke before the sandstorm and the Qing cavalry could come to turn the tide?