in the Old Testament (2 Samuel), a Jewish military commander under King David, who was his mother's brother. He led the commando party that captured Jerusalem for David and as a reward was appointed commander in chief of the army. He played a leading part in many of David's victories (e.g., against the Ammonites and the Edomites) and led the loyal force that crushed the rebellion of David's son Absalom. Utterly devoted to David, Joab believed that he knew David's interests better than David himself did; hence he killed Absalom, although David had commanded that his life be saved. Joab showed his characteristic ruthlessness in the treacherous murder of two of his potential rivals, Abner and Amasa. Joab obeyed under protest when ordered by David to carry out a national census. During David's last days, Joab supported the abortive bid for the throne by David's son Adonijah and was executed by the successful Solomon.