"Sudden as hungry wolves the kids purloin
Or lambs, which haply some unheeding swain
Hath left to roam at large the mountains wild;
They, seeing, snatch them from beside the dams,
And rend incontinent the feeble prey"
It actually does include the last two lines because those two definitely do not relate to armies (soldiers are not snatched from dams). The author is comparing the wolves and lambs to the armies.
