Albert Barnes Commentary 2 Samuel 11:21

"who smote Abimelech the son of Jerubbesheth? did not a woman cast an upper millstone upon him from the wall, so that he died at Thebez? why went ye so nigh the wall? then shalt thou say, Thy servant Uriah the Hittite is dead also." — 2 Samuel 11:21 (ASV)

Who smote Abimelech ... - This reference indicates that in David’s time, the national annals of that period existed in an accessible form, and that the king had a habit of reading, or having read to him, the history of his country .