Joshua went that night into the.... valley (Emek). — Not the ravine (or Gai) before mentioned (Joshua 8:11), but a wider and more open part of the valley, probably a little further to the south;· the object being to draw the men of Ai into a pursuit in the direction of the road to Gilgal.
Related Commentaries of Joshua 8:13
Joshua 8:13
13 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.