As we learned in II Kings 8, Jehoshaphat’s eldest son Jehoram inherited the throne, and his wife Athaliah converted him to the worship of Baal and Asherah. But Jehoshaphat was a considerate father and left all of his sons wealthy and in charge of their own cities. This made Jehoram uneasy, so as soon as he had solidified his power in Jerusalem, he murdered all of his brothers and a few Israelite princes (relatives of his wife) just to safe.
Unfortunately, this didn’t bring stability, because Edom rebelled against Judah, and so did other tribute nations, and Judah lost.
Then Elijah sent Jehoram a letter informing him that God was pissed he was cheating on It–and that he had killed his brothers, too–but mostly for cheating on It! so God would visit a plague on Judah that would cause Jehoram to shit his guts out.
And lo, first the Philistines and Arabians invaded Judah and plundered Jerusalem and killed all but one of Jehoram’s sons. Then some horrible GI plague attacked the land, and Jehoram was not spared. He suffered for two years before he finally shit his guts out and died. His reign was a mere 8 years long. No one was sad to see him go. In fact, he was so despised that there were no mourning ceremonies and his body was not entombed with the kings.