Give an example of one way the Yankee tried to undermine the knights.
Another way Hank tries to undermine the knights is to do away with the tournament. He hates the chivalric code and everything to do with it. So he tries to get the knights to play baseball instead of jousting and fighting in a melee. The problem is that the knights still wear their armor in the baseball game.
One examples of undermining the knights is when the Yankee gives them all bicycles to ride instead of manning their usual horses. I can imagine that is must have been quite amusing to see them all in their armor mounting and riding bikes...nothing of the romantic idealism in that scene.