The people had done as they asked, and then made assumptions of what the next best course might be. They felt that they were prepared, and sufficiently repentant that the Lord would be on their side. They ask Gidgiddoni to “let us go up upon the mountains … that we may fall upon the robbers and destroy them in their own lands.”
Gidgiddoni realized that while they were strong, the Gadiantons were not only stronger, but that they probably had better defensive positions in mountains that they knew well. While difficult for some to understand, rather than attack, Gidgiddoni has them wait to be attacked. He them promises that this tactic will allow them to have a victory.
Perhaps the most difficult thing to do in hard times is wait for the victory which will only come later.