When the Syrians saw that they were put to the worse before Israel, they sent messengers, and drew forth the Syrians who were beyond the River, with Shophach the captain of the host of Hadarezer at their head.
We have thoroughly discussed these nineteen verses in chapter 10 of 2Samuel, where they are found parallel to all that is written here.  These comments are on pp. 123-132 of my commentary on 2Samuel.  There is nothing further which I wish to add here.