C. F. Keil and Franz Delitzsch on 2 Samuel 11:17

2Sa 11:17 “And the men of the city came out (i.e., made a sally)and fought with Joab, and some of the people of the servants of David fell, and Uriah the Hethite died also.” The literal fulfilment of the king’s command does not warrant us in assuming that Joab suspected how the matter stood, or had heard a rumour concerning it. As a general, who was not accustomed to spare human life, he would be a faithful servant of his lord in this point, in order that his own interests might be served another time.