it came to pass. Compare the parallel (2 Samuel 8:1-8); and note that the two accounts are supplementary and complementary, not contradictory.
Gath. See note on "Metheg-ammah" (2 Samuel 8:1). In the time of Solomon (1 Kings 2:39 Gath was tributary.
her towns. Hebrew her daughters. Figure of speech Prosopopoeia. App-6.