Thematic Bible: David defeats an army and the ammonites at

So they hired for themselves 32,000 chariots, and the king of Maacah and his people, who came and camped before Medeba. And the sons of Ammon gathered together from their cities and came to battle. When David heard of it, he sent Joab and all the army, the mighty men. The sons of Ammon came out and drew up in battle array at the entrance of the city, and the kings who had come were by themselves in the field. read more.
Now when Joab saw that the battle was set against him in front and in the rear, he selected from all the choice men of Israel and they arrayed themselves against the Arameans. But the remainder of the people he placed in the hand of Abshai his brother; and they arrayed themselves against the sons of Ammon. He said, "If the Arameans are too strong for me, then you shall help me; but if the sons of Ammon are too strong for you, then I will help you. "Be strong, and let us show ourselves courageous for the sake of our people and for the cities of our God; and may the LORD do what is good in His sight." So Joab and the people who were with him drew near to the battle against the Arameans, and they fled before him. When the sons of Ammon saw that the Arameans fled, they also fled before Abshai his brother and entered the city. Then Joab came to Jerusalem.