But the sons of Fëanor knew that Morgoth would betray them, and would not release Maedhros, whatsoever they might do; and they were constrained also by their oath, and might not for any cause forsake the war against their Enemy. Therefore Morgoth took Maedhros and hung him from the face of a precipice upon Thangorodrim, and he was caught to the rock by the wrist of his right hand in a band of steel.
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But the sons of Fëanor knew that Morgoth would betray them, and would not release Maedhros, whatsoever they might do; and they were constrained also by their oath, and might not for any cause forsake the war against their Enemy. Therefore Morgoth took Maedhros and hung him from the face of a precipice upon Thangorodrim, and he was caught to the rock by the wrist of his right hand in a band of steel.
I'd say it was pretty much cause-and-effect.