Wubei Zhi (Vol. 47)

...if a state of strict alert martial law original: 戒嚴 (jieyan); here referring to a heightened state of security where movement is restricted. is imposed, no one is permitted to leave their assigned post original: 信地 (xindi); the specific sector or "ground of trust" a soldier is sworn to protect. to provide reinforcement elsewhere. This is for fear that the enemy might "make a feint in the east while attacking in the west" original: 聲東擊西 (sheng dong ji xi); a classic military stratagem where a diversion is created to draw defenders away from the intended point of attack., taking advantage of a gap to scale the walls. In this way, the defense remains tight and the response calm and orderly. Should the tower soldiers fail due to error, they shall be severely punished according to military law.

Establishing Patrols

The diligence of soldiers stationed at the battlements original: 垜兵 (duobing); infantry assigned to the crenelated sections of the wall. varies. It is necessary to constantly inspect them. However, if one makes everyone answer a roll call with loud shouting at every watch, those guarding the battlements will be unable to sleep. They will become physically and mentally exhausted, which is not a sound strategy. Instead, use the city gates as boundaries—for example, the stretch from the East Gate to the South Gate. At each gate, ten patrol soldiers shall be stationed. They shall be provided with one small red flag inscribed with the word "Patrol." For each watch, two soldiers shall take their turn, patrolling back and forth in continuous succession. Each shall simply carry a lantern and hold the flag while moving between the battlement openings. Shouting or striking signals is strictly forbidden. The text warns against "striking" (da), likely referring to the practice of hitting wooden clappers or drums to mark time, which would disturb the sleeping guards.