固壁清野

Explanation: Solid wall, that reinforced barriers, so that the enemy is not easy attacks; Qing Ye, that the transfer of population, goods, so that nothing for the enemy. This is the advantage against the enemy invasion of a strategy. 　　Source: "Hun Li Chuan Qi book" Community-off (Cui community off) veterans resourceful, wise city of their own security, the solid wall of opposition clear. "