Charles Ellicott Commentary Genesis 48:19

"And his father refused, and said, I know [it], my son, I know [it]. He also shall become a people, and he also shall be great: howbeit his younger brother shall be greater than he, and his seed shall become a multitude of nations." — Genesis 48:19 (ASV)

His younger brother shall be greater. —In the final numbering of the tribes on the plains of Moab, the tribe of Manasseh had 52,700 souls, and that of Ephraim only 32,500 (Numbers 26:34; Numbers 26:37).

It was the division of the tribe of Manasseh into two portions that made it politically insignificant, while Ephraim obtained a commanding position in the land of Canaan; and as Joshua was an Ephraimite, Ephraim naturally held the rank of foremost tribe during his days and claimed it always afterwards. For Joshua, after the conquest of Canaan, must have held a position similar to that of General Washington after the independence of the United States had been secured, and all Israel would have regarded him as their ruler and chief. Ephraim's influence was also strengthened by the ark being placed in one of its towns.