This is an added detail this time around, and it points to one of the reasons for the heavy loss. The Israelites only have swordsmen for soldiers, while the Gibeonites have the 700 stone-slingers (Judges 20:16), who have long-range attack abilities. So far they have therefore made it impossible for the Israelites to get close enough for hand-to-hand combat. So the Israelites need to find better tactics if they are going to succeed in battle.”1
25 And Benjamin went against them out of Gibeah the second day, and destroyed 18,000 men of the people of Israel. All these were men who drew the sword.