军临城下

Explanation: The enemy has come to their own walls below. Analogy the situation very critical. 　　Source: "Warring States II QI strategy": "Qi will give Bingfa beam, beam, together with the soldiers can not go under in the city, with its thinning Han Wang." 　　Examples: Marshal ~, approaching trench edge, gaze down the Southern Tang is also a drum. (Ming Anonymous "under the shadow of southern Cao," the third off)