1 Chronicles 19:9

And the children of Ammon came out, and put the battle in array before the gate of the city: before their capital, Rabbah, the forts of the city thus serving to cover their rear. And the kings that were come were by themselves in the field; the mercenaries did not effect a union with the army of the Ammonites, but prepared to attack the forces of Israel from the north, from the flank or the rear.