《三国志·魏书·武帝纪》
半夜里派兵偷袭围城的曹军。曹公迎战袁军，大败袁军，并下令乘胜包围他们的营寨。
夜遣兵犯围，公逆击破走之，遂围其营。
In the middle of the night, he sent troops to attack the Cao army besieging the city. Cao Cao met the Yuan army and defeated them badly, and ordered his troops to take advantage of the victory and surround their camp.