Joshua 8:13

And when they had set the people
In battle array, as in ( 1 Kings 20:12 ) ; that is, Joshua and the officers of the army:

[even] all the host that [was] on the north of the city;
where Joshua and the main army were:

and the liers in wait on the west of the city:
both the first and second ambush; when all, were prepared and got ready by their several officers, to act the part they were to do:

Joshua went that night into the midst of the valley;
according to Ben Gersom, to see whether the guards or sentinels which were placed there were awake or asleep, lest the men of Ai should come suddenly upon them and smite them; but perhaps it might be to pray and meditate.