Genesis 49:19 - Matthew Poole's English Annotations on the Holy Bible

i.e. Troops of enemies shall frequently invade his country, and for a time conquer and spoil it. And so it came to pass, because the inheritance of that tribe lay beyond Jordan, near to the Ammonites and Moabites, two inveterate enemies of Israel, and to other hostile nations on the east. But he shall overcome at the last, or, afterward. This was fulfilled, 1 Chronicles 5:18, &c. He shows that the events of the wars should be various, but Gad should one time or other spoil his spoilers. See Deuteronomy 33:20.