Boyd’s Bible Dictionary:
(troop). (1) Jacob’s seventh son (Gen. 30:11-13; 49:19; Num. 1:24-25). Tribe settled east of Jordan, and became a fierce, warlike people. Carried captive by Tiglath-pileser (1 Chron. 5:26). (2) A prophet and David’s seer (1 Sam. 22:5; 1 Chron. 21:9-19; 29:29; 2 Chron. 29:25).
Concise Bible Dictionary:
The seventh son of Jacob, and the first of Zilpah, Leah’s maid. Very little is recorded of Gad, except that he had seven sons (Gen. 30:11; Gen. 46:16; 1 Chron. 5:11). Jacob in blessing his sons said of Gad, “A troop shall overcome him but he shall overcome at the last” (Gen. 49:19). Moses said, “Blessed be he that enlargeth Gad: he dwelleth as a lion, and teareth the arm with [or rather, “even”] the crown of the head. And he provided the first part for himself, because there, in a portion of the lawgiver, was he seated; and he came with the heads of the people, he executed the justice of the Lord, and his judgments with Israel” (Deut. 33:20-21). On leaving Egypt the number of those able to bear arms was 45,650, but on the crossing of the Jordan their number was about five thousand less.
Being on the east of Jordan, this tribe, with Reuben and Manasseh, would necessarily have to bear the shock of the enemies that attacked Israel on the east (1 Chron. 5:18-22). They were a warlike tribe, suitable for such an exposed position. Of those who joined David it is said they were “men of might, and men of war fit for the battle, that could handle shield and buckler, whose faces were like the faces of lions, and were as swift as the roes upon the mountains” (1 Chron. 12:8-15). Jephthah and Barzillai were of this tribe.
Gad possessed a large district from a little above the north corner of the Dead Sea to near the south corner of the Sea of Galilee, then a very fertile plain suitable for their flocks and herds, including the highlands of Gilead (see map under TWELVE TRIBES). The tribes on the east of the Jordan were the first carried away by the king of Assyria, about B.C. 740; and the Ammonites took possession of the territory of Gad (1 Chron. 5:25-26; Jer. 49:1). Twelve thousand of this tribe will in a future day be sealed for blessing (Rev. 7:5). Their allotment will be in the extreme south in the restoration of Israel (Ezek. 48:27).