Yes, MississaugRed, you're right - self-forged chains are the strongest and the ones we're least likely to break.I think. Ennis was starting to break the ones he ( and his father) had imposed on him, but too late; of course Jack had kept Ennis on a short leash in the sense that he'd created in Ennis a paralysing terror that prevented him from responding fully to Jack.
Perhaps that's part of BBM's message, that we shouldn't chain ourselves down by fear and hate?