In the eighteenth year of Jehoshaphat - This date agrees exactly with the statements that Jehoshaphat began to reign in the fourth year of Ahab 1 Kings 22:41, and Ahaziah in the 17th year of Jehoshaphat 1 Kings 22:51.
Related Commentaries of 2 Kings 3:1
2 Kings 3:1
1 Now Jehoram the son of Ahab began to reign over Israel in Samaria the eighteenth year of Jehoshaphat king of Judah, and reigned twelve years.