Chief Hugh's battle company attempted to retake Isengard after the War of the Ring (I know we are messing with canon here, but who cares). Spoilers, his company succeed. Here is the board we set up. Riders of Rohan, and an ent defended against his roughly 200 point Dunland BC.

Correction : Dunland took Isengard.
The story is that the tribes of Dunland after seeing Saruman defeated at helms deep and at Isengard itself, see a opportunity. With the white wizard cast out from the tower of Orthanc, it left a power vacuum in the area. Dunland, goblins, etc. all try to take Isengard for themselves.