《后汉书·列传·袁绍刘表列传上》
袁绍挖掘地道想偷袭曹操，曹操马上在营内挖出很长的壕沟拦住袁绍，并且派奇兵偷袭袁军的运粮车，将其粮食全部烧毁。
绍为地道欲袭操，操辄于内为长堑以拒之。又遣奇兵袭绍运车，大破之，尽焚其谷食。
Yuan Shao dug a tunnel to sneak attack Cao Cao, so Cao Cao immediately dug a very long trench in the camp to block Yuan Shao and sent a surprise team to attack Yuan's army's grain transportation carts, burning all their food.