Joshua 8:14 (KJV)

And he took about five thousand men, and set them to lie in ambush between Beth–el and Ai, on the west side of the city.

And when they had set the people, even all the host that was on the north of the city, and their liers in wait on the west of the city, Joshua went that night into the midst of the valley.

And it came to pass, when the king of Ai saw it, that they hasted and rose up early, and the men of the city went out against Israel to battle, he and all his people, at a time appointed, before the plain; but he wist not that there were liers in ambush against him behind the city.

And Joshua and all Israel made as if they were beaten before them, and fled by the way of the wilderness.

And all the people that were in Ai were called together to pursue after them: and they pursued after Joshua, and were drawn away from the city.