Jehoshaphat establishes a justice system with the supreme court in Jerusalem - 2Chr19
Moab, Ammon, and Edom come against Judah. Jehoshaphat prays, appealing to Solomon's prayer. God responds and the enemy turns against each other. Jehoshaphat was a good king, though the people insisted on their high places and he kept allying with wicked Israel - 2 Chr 20.
Jehoshaphat's son Jehoram king for 8 years. started by killing all his brothers. Nations around revolted during his reign. His own wives and children killed or captured, except Jehoahaz (Ahaziah) - 2 Chr 21.
Ahaziah king one year. Follows Ahab in idolatry. Fights as ally with Ahab's son. Killed with him by Jehu. Athaliah, Ahaziah's mother, kills the whole family, but 1-year-old Joash saved by Joshabeath, wife of Jehoiada and daughter of Ahaziah - 2 Chr 22.
Jehoiada the high priest guards the purity of the temple and so protects the king. He organizes supporters for Joash and crowns him. Athaliah is killed - 2 Chr 23.