zhǔ / lì / chè / tuì / hòu / lǎo / ruò / cán / bīng / bèi / liú / xià / lái / shǒu / zhù / yíng / dì

主力撤退后，老弱残兵被留下来守住营地。

After the main force withdrew, the remnants of the defeated army were left to guard the camp.