2 Samuel 18:6

So the people went out into the field against Israel: and the battle was in the wood of Ephraim;

The battle between David's forces and Israel took place in the wood of Ephraim, near the Jordan. The forest with its thickets and marshes left Absalom's much larger, undisciplined army confused and unmanageable, so that its superior numbers became a disadvantage rather than a strength. Twenty thousand men were killed in the fighting, and Absalom himself was captured and killed.