Why does it say "Haysah" (feminine)?
Radak: It refers to "Milchamah", and not to "Pnei". We find like this - "Keshes Giborim Chatim" (1:2:4), "Kol Negidim Nechba'u" 1 (Iyov 29:10).
I.e. Nechba'u refers to Negidim, and not to Kol.
What is "Pnei ha'Milchamah"?
Radak: It is Pnei ha'Giborim. They are Pnei ha'Milchamah, for they go in front. Yonason translates '[was strong against him] those who make war.'
Why did Yo'av go to fight Aram, and not Amon?
Malbim: He feared to fight Amon at the opening of the gate of Rabah 1 , for then the kings in back will come upon him, and he will be between two strong camps. The kings themselves were strong, and Amon was strong because they were by the fortified city. Therefore, he was wise to fight first the kings by Meidva. He left his weak men with Avishai, so if Amon goes out [to help Aram], Avishai will defeat them.
Malbim learns from 11:1 that they were by the gate of the city Rabah. (PF)
