See, this is why chess only works as a metaphor for war to a certain point.
Even disregarding the numeric disadvantage, chess doesn't have rules for the morale of a knight being so low and pawns being so high that when a rook moves to take a pawn, it's the one that falls instead. Not to mention maneuverability. Rooks aren't ever too tired to move more as much as they need to.
It's simple enough, but still satisfying to watch.