Genesis 49:19 - Joseph Benson’s Commentary on the Old and New Testaments

Concerning Gad, he alludes to his name, which signifies a troop, foresees the character of that tribe, that it should be a warlike tribe; and so we find, 1 Chronicles 12:8, the Gadites were men of war fit for the battle. He foresees that the situation of that tribe on the other side Jordan would expose it to the incursions of its neighbours, the Moabites and Ammonites; and that they might not be proud of their strength and valour, he foretels that the troops of their enemies should, in many skirmishes, overcome them; yet, that they might not be discouraged by their defeats, he assures them that they should overcome at the last Which was fulfilled, when in Saul's time and David's the Moabites and Ammonites were wholly subdued.