During Jehoram's rule Edom rebelled against Judah's power and appointed their own king.
Jehoram along with all his chariots crossed over to Zair. He got up at night to attack the Edomites who had surrounded him and his chariot commanders, but his army fled back home.
So Edom has been independent of Judah to this day. Libnah rebelled at the same time.