And Ahab king of Israel said unto Jehoshaphat king of Judah, Wilt thou go with me to Ramothgilead? And he answered him, I am as thou art, and my people as thy people; and we will be with thee in the war. To Ramoth-gilead - This place belonged to the Israelites, and was now held by the king of Syria.
The whole of this chapter is circumstantially explained in the notes on 1 Kings 22:1-53.