It occurs to me now that this echoes a scene late in Moby Dick in which Ahab smashes his sextant to the deck and declares that henceforth he will navigate by dead reckoning alone, without reference to the sun or stars or like works of God.
Captain Ahab is mortal and goes down with all but one of the crew of the Pequod, like Glanton who dies along with most of his gang at the hands of the Yuma. Both leaders are proud and defiant to the last and are justly killed (though we have to feel first mate Starbuck at least deserved better).
Both Glanton and Ahab are undisputed masters of their respective expeditions, and both leave behind young families at the outset, though for different reasons: Glanton flees the law, Ahab sails voluntarily.