Jehoshaphat being then king. Jehoram associated with him in Joram's filth year, and reigned solely in Joram's sixth year. Compare 2 Kings 9:29. Joram (of Ahab) began in Jehoshaphat's eighteenth year (2 Kings 3:1). His fifth year is therefore Jehoshaphat's twenty-third year, when Jehoram is associated with him as king, in the third year before his death. See App-50.
began to reign: i.e. in consort with his father.