《尉缭子·勒卒令》
一般说未正兵应该先用，奇兵应该后用，但是哪个先用，哪个后用，都是为了战胜敌人。
故正兵贵先，奇兵贵后，或先或后，制敌者也。
It is generally said that the regular troops should be used first, and the surprise troops should be used later. However, which is used first and which is used later, are all for the purpose of defeating the enemy.