《资治通鉴·陈纪·陈纪三》
以我方深入前敌的孤军，去攻打对方严阵以待的军垒，如果不能一仗攻克，会更加助长他们的气焰。
以我悬军，攻其严垒，脱一战不克，更成其气。
With our army of isolated troops going deep into the enemy's territory to attack the enemy's heavily guarded military fortress, if we fail to capture it in one battle, it will only boost their morale.