A “sounder” of piglets assaulting the cat fort.
I’ve always been fascinated by the names we have for various groups such as, “murder” of crows, “prickle” of porcupines, etc. I found this site which has more collective nouns than I knew existed.
The boys made a play area for the kittens by placing green tree leaves in a tray outside of the fort. The piglets devoured the leaves, but failed to breach the blanketed interior of the fort.