David mustered the men who were with him and appointed over them commanders of thousands and commanders of hundreds.
References for 2 Samuel 18:1
David sent the troops out1--a third under the command of Joab, a third under Joab's brother Abishai2 son of Zeruiah, and a third under Ittai3 the Gittite. The king told the troops, "I myself will surely march out with you."
References for 2 Samuel 18:2
But the men said, "You must not go out; if we are forced to flee, they won't care about us. Even if half of us die, they won't care; but you are worth ten4 thousand of us. It would be better now for you to give us support from the city."5
References for 2 Samuel 18:3
The king answered, "I will do whatever seems best to you." So the king stood beside the gate while all the men marched out in units of hundreds and of thousands.
The king commanded Joab, Abishai and Ittai, "Be gentle with the young man Absalom for my sake." And all the troops heard the king giving orders concerning Absalom to each of the commanders.
The army marched into the field to fight Israel, and the battle took place in the forest6 of Ephraim.
References for 2 Samuel 18:6
There the army of Israel was defeated by David's men, and the casualties that day were great--twenty thousand men.
The battle spread out over the whole countryside, and the forest claimed more lives that day than the sword.