14 So it happened that when the king of Ai saw all this, the men of the city lost no time; they were out of there at the crack of dawn to join Israel in battle, the king and his troops, at a field en route to the Arabah. The king didn't know of the ambush set against him behind the city.
Matthew Henry's Commentary on Joshua 8:14
Commentary on Joshua 8:3-22
(Read Joshua 8:3-22)
Observe Joshua's conduct and prudence. Those that would maintain their spiritual conflicts must not love their ease. Probably he went into the valley alone, to pray to God for a blessing, and he did not seek in vain. He never drew back till the work was done. Those that have stretched out their hands against their spiritual enemies, must never draw them back.