Genesis 48:21

‘And Israel said to Joseph, “Behold I die. But God will be with you and bring you again to the land of your fathers. Moreover I have given to you one portion above your brothers, which I took out of the hand of the Amorite with my sword and with my bow.”

Jacob prophesies the future return to the land. Joseph will return in his descendants to the land of his fathers. Perhaps it was Jacob's intention that Ephraim and Manasseh should lead the return.

“One portion (shechem) above your brothers.” This is because now Joseph's portion is twofold in that Ephraim and Manasseh have become full sons, each entitled to their full share in the inheritance.

“Which I took out of the hand of the Amorite with my sword and with my bow.” This unknown incident clearly refers to some area outside the promised land which Jacob and his tribe took by force, and which Jacob now sees as made part of that land. This, he feels, is what gives him the right to give a portion to both Ephraim and Manasseh. He has extended the promised land. It was possibly in the hill country beyond Jordan, which was seen as Amorite country (Numbers 13:29). It is possibly not without significance that that was where the half tribe of Manasseh received their portion. This is a rare example to remind us that much of the story of the patriarchs we do not know, only what was connected with covenants. We do not tend to think of Jacob as a warrior, but clearly he could be as warlike as his father Abraham.

Some have referred it to the Shechem incident but Jacob was there displeased with his sons' actions, and Shechem was part of the promised land already.