《明史·列传·卷一百三十八》
现在敌人在关城内，关城不能够防守，卫城与关城相连，可以步行上去。
今敌在内，关城无可守，卫城连关，可步屟而上也。
Now the enemy is inside the outer city, which cannot be defended, and the inner city is connected to the outer city, accessible on foot.
<s>[INST] Identify the key themes in this Classical Chinese text and explain them in English: 今敌在内，关城无可守，卫城连关，可步屟而上也。 [/INST] Now the enemy is inside the outer city, which cannot be defended, and the inner city is connected to the outer city, accessible on foot.</s>
Identify the key themes in this Classical Chinese text and explain them in English: 今敌在内，关城无可守，卫城连关，可步屟而上也。
user
Now the enemy is inside the outer city, which cannot be defended, and the inner city is connected to the outer city, accessible on foot.
assistant