As David’s army was to go out to battle Absalom and his men, he planned to go with them. Why do you suppose that is? Do you think it’s because the last time they went out and he stayed home, that’s when all the trouble began? Yeah, me too. I think he figured he’d rather die in battle than have something like that happen again.
But his men convinced him that he was much more valuable alive than dead.
And of course you heard David’s order, as well as his army, that Absalom was not to be hurt. But as Absalom’s forces were being slaughtered to the tune of 20,000 men dead, he mounted he mule and tried to flee. Remember how proud he was of his hair? Now it is that of which he is proud that traps him. (There’s a whole sermon in itself.) His hair gets caught by a low hanging branch of an oak tree, and Absalom is unable to free himself.
When one of Joab’s soldiers reports to him what happened, Joab finds out that the man didn’t finish off Absalom because he was afraid of what would happen to him when David learned that his order to leave Absalom unharmed was disobeyed. So Joab goes to where Absalom is hanging, and runs him through three times with spears and then has ten of his men finish him off.
The question is, why did Joab disobey King David’s order? Well, as the general of the army, he was certainly a wise tactician. First, he knew that David had been a weak father. He hadn’t disciplined his children, and this is a big part of the reason that Absalom became the man he did. Second, Joab figured that if Absalom was spared, he might continue tearing the kingdom apart. And third, even if he didn’t continue in that, Absalom was next in line for the throne. Joab could see that this was not a man worthy to be king.
Joab actually did both David and the kingdom a favor by killing Absalom. David could get back to being the king without having to defend himself from his son, and the kingdom could reunite behind David.