During Jehoram’s reign, the Edomites revolted against Judah and crowned their own king.
So Jehoram went out with his full army and all his chariots. The Edomites surrounded him and his chariot commanders, but he went out at night and attacked them under cover of darkness.
References for 2 Chronicles 21:9
Even so, Edom has been independent from Judah to this day. The town of Libnah also revolted about that same time. All this happened because Jehoram had abandoned the LORD, the God of his ancestors.
He had built pagan shrines in the hill country of Judah and had led the people of Jerusalem and Judah to give themselves to pagan gods and to go astray.
Then Elijah the prophet wrote Jehoram this letter: “This is what the LORD, the God of your ancestor David, says: You have not followed the good example of your father, Jehoshaphat, or your grandfather King Asa of Judah.
Instead, you have been as evil as the kings of Israel. You have led the people of Jerusalem and Judah to worship idols, just as King Ahab did in Israel. And you have even killed your own brothers, men who were better than you.
So now the LORD is about to strike you, your people, your children, your wives, and all that is yours with a heavy blow.
You yourself will suffer with a severe intestinal disease that will get worse each day until your bowels come out.”