Crowded, in a confined space. The term comes from eighteenth-century naval warfare. Wooden barriers were placed at various points on a ship, so that when an enemy boarded, the crew could retreat behind them and fire at the enemy through loopholes. The crew then were said to be fighting in close quarters, that is, in close contact with the enemy. The term later was transferred to any close contact or crowded situation.

Show no mercy. This term comes from the ancient practice of sparing the life of an enemy who has come into one’s power, which was described as giving or granting quarter. Granting no quarter meant they were killed. The meaning of “quarter” has been disputed. The most likely explanation lies in “quarters” in the sense of “barracks,” a use of the word since the late sixteenth century. To grant no quarter thus meant to provide no housing for prisoners, who of course would not need it if they were dead. Wrote Nathan Bailey in 1725 (trans. Erasmus’ Colloquies), “It is grown into a proverb, I’ll give you no more quarter than a dog does a wolf.”