Chapter 61
備突
Preparation against a Sally
城百步一突門，突門各為窯灶，竇入門四五尺，為亓門上瓦屋，毋令水潦能入門中。吏主塞突門，用車兩輪，以木束之，塗其上，維置突門內，使度門廣狹，令之入門中四五尺。置窯灶，門旁為橐，充灶伏柴艾，寇即入，下輪而塞之。鼓橐而熏之。
In the wall, there should be one sally port every 100 bu. For each sally port, there should be a kiln or furnace and a tuyere which enters the gate for 4 or 5 chi. Above the gate, construct a tiled roof that does not allow water or heavy rain to enter the gate. An officer controls the blocking of the sally port using two cart wheels bound together with wood and smeared with mud on the upper surface. Suspend this structure within the sally port, letting it be commensurate in width with the sally port. Let the tuyere enter the gate for 4 or 5 chi. Set up the kiln or furnace and place bellows beside the gate. Fill the furnace full with firewood and artemisia. When the enemy enters the gate, drop the wheels and block it. Activate the bellows and create smoke.