Sentence:  The sun had shifted round, and the myriad windows of the Ministry of Truth, with the light no longer shining on them, looked grim as the loopholes of a fortress. His heart <WSD>quailed</WSD> before the enormous pyramidal shape. It was too strong, it could not be stormed. 
Meaning of the word marked with <WSD> tags:  To lose heart or courage; to be daunted or fearful. (from 16th c.)