Yes. Because Cassius was the one who started the events that led onto Caesar's death and eventually on to his own death. Brutus did not like that Cassius was being un-loyal towards his own brother-in-law and therefore spoke up about it when they talked in the tent it act 4.
The Knight is dressed in a tunic made of coarse material ; he wears a suit of armor that is stained by rust. He has a horse which he take care of it better than himself.
We just finished Animal Farm Yesterday So, here is What I think