John Carter calling out Tal Hajus as a Dirty Coward. He's a human being amongst a band of the giant green men of Barsoom, who has been sentenced to death by Tal Hajus. But over the course of the novel, John Carter has not only mastered the languages and customs of Barsoom, but twice earned himself a place as a chieftain of the Thark. And at that moment, he uses all of that amassed knowledge and reputation to turn the assembled Tharks against their king and in favor of himself and Tars Tarkas. He also ensures that Tars Tarkas is the one who administers the death blow, knowing that his Barsoomiam friend has a very large grievance against Hajus.
Carter leading a slave rebellion in the Ampitheater of Issus, rousing a multitude of prisoners who moments before were completely broken to rebel against their masters. The chapter is fittingly titled "When Hell Broke Loose."
The duel between Carter and Solan, described as the greatest opponent he ever had despite being a very old man. Carter only wins because his goal is not to kill Solan, but get past him to push a switch, and upon doing it Solan is distracted enough for him to slip a killing thrust in.