“When Joab saw that the line of battle was set against him both in front and in the rear, he chose some of the picked men of Israel, and arrayed them against the Arameans. The rest of his troops he put in the charge of his brother Abishai. They were arrayed against the Ammonites. He said. ‘If the Arameans are too strong for me, then you shall help me. But if the Ammonites are too strong for you, then I will help you. Be strong. Let us be courageous for our people, and for the cities of our God. May Yahweh do what seems good to him.’ So Joab and the troops who were with him advanced forward toward the Arameans for battle. The Arameans fled before him. When the Ammonites saw that the Arameans had fled, they likewise fled before Abishai, Joab’s brother. Abishai and Joab entered the city. Then Joab came back to Jerusalem.”
Once again, this biblical chronicler followed almost word for word 2 Samuel, chapter 10. When Joab saw the setup he broke his troops into 2 sections with his brother Abishai in charge of one section and he the other. One would fight the Ammonites and the other would fight the Arameans. Yahweh would do what was good for him. As it turned out, both groups fled, so that Joab returned to Jerusalem.