Jehoram ruled Israel for 12 years. God didn’t really like him, but thought he was better than his parents since he didn’t worship Baal.
Meesha, the king of Moab a vassal kingdom of Israel, thought that the confusion over succession seemed like a good time to rebel against them, and refused to send the ton of wool or herds of lambs Israel demanded yearly as tribute. So Jehoram sent a message to Jehoshaphat asking for help putting the rebellion down. It was decided that they would take the roundabout way into Moab by marching through the desert of Edom, a vassal kingdom of Judah. So they set out, but after a week, they weren’t there yet, and they had run out of water. After some pondering, the kings decided to consult Elisha, who happened to be handy. At first, Elisha was all rude to Jehoram, but he consented to talk to God out of respect for Jehoshaphat. So he called for a musician and in the music, he heard God or something, and he told the kings that in the morning, the arroyo would be filled with water, though no rain would fall.
Next morning, when the nearby Moabite troops looked out and saw the sun glinting off the new-made pools, they assumed that it must be pools of blood from dissension between the Isrealites, Judaeans, and Edomites, and went to go plunder. Unfortunately, the Hebrews were ready for them, and completely routed them. The Hebrew forces then pursued the Moabites all the way back to Kir-hareseth. In a moment of utter desperation, Meesha sacrificed his son the crown prince to Chemosh, and this sacrifice rallied the troops to drive the Hebrews off.
By the way, the Hebrews also deliberately damaged every piece of arable soil or pasture they crossed in retaliation for the rebellion.