宋史
After losing half his army Wuzhu escaped back to the north, only to invade again in the following year. Again, he was defeated while trying to breach a strategic pass. The "History of Song" states that during the battle Wu Jie's brother Wu Lin "used the Standing-Firm Arrow Teams, who shot alternately, and the arrows fell like rain, and the dead piled up in layers, but the enemy climbed over them and kept climbing up." This passage is especially noteworthy for its mention of a special technique being utilized as it is one of the very few times that the "History of Song" has elaborated on a specific tactic.