In ROCH, there was a part where the Mongolians attacked Xiang Yang by forcing about 2000 civilians to go first with their army following closely behind. This led to the scene where GJ was climbing up the wall when the GWM ambushed him and YG rescued him.
Guo Jing immediately recognised this tactic as he had seen it many times before while he was a general under Genghis Khan, but he didnt know how to effectively counter it. The civilians were usually captured in nearby villages and therefore were likely to be families of the soldiers guarding the fortress. This usually forced the soldiers to open the gate and the Mongolian army would flood the fortress as that happened. Even if it didn't succeed, at least the Mongolians would get a few of their spies inside, not to mention demoralizing the other side.
If you were General Guo Jing, how would you counter this tactic? Yes you can ask your wife for help.