2 Kings 1:17

The similarity of names in the two royal houses of Israel and Judah at this time, and at no other, seems to be the consequence of the close ties which united the two reigning families, and is well noted among the “undesigned coincidences” of the Old Testament. The accession of the Israelite Jehoram (Ahab’s brother) took place, according to 2 Kings 3:1, in the eighteenth year of Jehoshaphat. Jehoram of Judah perhaps received the royal title from his father as early as his father’s sixteenth year, when he was about to join Ahab against the Syrians; the same year might then be called either the eighteenth year of Jehoshaphat or the second year of Jehoram.