I think the extended simile is "<span>Sudden as hungry wolves the kids purloin Or lambs, which haply some unheeding swain Hath left to roam at large the mountains wild</span>" that the soldiers are so overwhelmed with pride and honor and glory that they lose hope and they just fight and kill anything in thier path. I think it adds meaning to the text because the people who are going through this are so lost that they do whatever and dont care anymore.
