"Gave quarter" is a phrase that denotes showing mercy or leniency towards someone, usually in a conflict or battle scenario. The antonyms for this phrase would be quite varied depending on the context in which it is used. Opposite words or phrases could include terms such as "refused quarter," "withheld mercy," "showed no leniency," "denied clemency," or "exacted punishment." Each of these antonyms implies a different attitude or behavior towards the person in question, indicating a harsher or more uncompromising stance. Ultimately, the choice of antonym would depend on the specific situation and the intent of the individual involved.