It seems that Joab and his brothers were among the several hundred people who joined David during his flight from Saul. The private army that David formed from these people later became the central fighting force in his royal army (1 Sam 22:1-2; 26:6; 30:9; 2 Sam 2:13). (For map covering the region of David’s activities see DAVID.) In the two-year civil war that followed Saul’s death, Joab quickly established himself as David’s military leader (2 Sam 2:28). He was also a close relative of David (1 Chron 2:13-16). When Saul’s former commander, Abner, defected to David, Joab saw him as a threat and murdered him. Joab used the excuse that he was retaliating because Abner had killed his brother in battle. But David saw it as murder and never forgave Joab (2 Sam 2:12-23; 3:23-39; 1 Kings 2:5-6).
Not long after these events, David became undisputed king of Israel. In response to David’s declaration that he wanted to take Jerusalem from its Canaanite inhabitants, Joab led a victorious assault on the city and was rewarded by being appointed commander-in-chief of the Israelite army (1 Chron 11:6; 18:15). He was a clever, brave and loyal soldier (2 Sam 10:6-19; 11:1; 12:26) who usually had David’s interests at heart (1 Sam 12:27-28; 24:2-4). Nevertheless, had had no excuse for cooperating with David in the killing of Uriah (2 Sam 11:6-25). When, as a consequence of David’s wrongdoing, his family started to break up, Joab tried to preserve the dynasty by ensuring that there was a recognized heir to the throne. He considered that the most suitable of David’s sons for the position was Absalom, but Absalom had committed murder and fled to a neighbouring country. Joab therefore worked out a clever plan that enabled Absalom to return from exile without having to stand trial (2 Sam 14:1-24). Once back in Jerusalem, Absalom heartlessly used Joab to pursue his own ambitions (2 Sam 14:28- 33). When Absalom rebelled against David and seized the throne, Joab again upheld David. He brought the rebellion to a swift end by killing Absalom, even though it was against David’s wishes (2 Sam 18:2,5,9-16).
He then rebuked David for his lack of gratitude to those who had saved him (2 Sam 19:1-8). Upon resuming his rule in Jerusalem, David appointed Absalom’s general, Amasa, chief of the army in place of Joab. This was clearly unfair to Joab, who had been loyal to David and won him the victory (2 Sam 19:13). Soon there was another uprising against David. When Amasa proved himself to be a poor leader, Joab murdered him and took control of the army as of old (2 Sam 20:4-10,23). In the palace conflict to decide which son would succeed the ageing David as king, Joab supported Adonijah in opposition to Solomon, who was David’s choice (1 Kings 1:5-8,13,19; 1 Chron 28:5). On becoming king, Solomon executed Joab. A violent death seemed a fitting end for one whose life had been marked by so many acts of violence (1 Kings 2:28-35).