Joshua 8:10-13

Early the next morning Joshua roused his men and started toward Ai, accompanied by the elders of Israel. All the fighting men who were with Joshua marched in front of the town and camped on the north side of Ai, with a valley between them and the town. That night Joshua sent about 5,000 men to lie in ambush between Bethel and Ai, on the west side of the town. So they stationed the main army north of the town and the ambush west of the town. Joshua himself spent that night in the valley.