Or HaChaim on Genesis 49:19/אור החיים על בראשית מ״ט:י״ט

1 גד גדוד יגודנו, "Gad, a troop shall troop upon him, etc." Jacob links his blessing to his name, interpreting his name as meaning "a troop, a camp," as well as גדיה. The author refers the reader to the Sefer Ha-aruch which describes the word גד also as meaning "to draw," "to lead," and "to surround." Accordingly, the meaning is that Gad will surround his enemies. When Jacob continued: והוא יגוד עקב, this means that he will utterly destroy them to the heel, i.e. the lowest extremity. Gad will surround the entire camp of Israel and fight on their behalf. עקב may also refer to the fact that he would help them to receive their reward, their inheritance, [all this is a reference to when the two and a half tribes led by Gad undertook to form the vanguard in the conquest of the land of Canaan in Numbers 32,32. Ed.]