What does 1 Kings 22:30 mean?

Ahab said to Jehoshaphat, 'I’ll disguise myself when we go into battle, but you wear your royal robes.' So the king of Israel disguised himself and went into the fight. 1 Kings 22:30 - Modern Text Bible

(Ahab tries to avoid being targeted by dressing like a regular soldier, while Jehoshaphat stays in his royal clothes.)