The underlying theme of this part of Moroni’s argument is the covenant of the land. There is protection upon principles of righteousness. In the current war, there have been many Nephites who have died, and Moroni makes certain that he notes that they died defending Nephite ideals, and not because they were unrighteously violating them.
The blame is not that those brave men who died were not living up to their covenants, but rather that the very fact that the Nephites were engaged in this war was evidence that those who were “at our head” had brought the war upon the nation through their unrighteousness.
Moroni is placing Pahoran among those who are unrighteously causing the overall protection of the Lord to be withdrawn. This is Moroni’s message in verse 15.