Joshua 8:7, 9, 12, 14, 19

you will jump up from your ambush and take possession of the town, for the LORD your God will give it to you.

So they left and went to the place of ambush between Bethel and the west side of Ai. But Joshua remained among the people in the camp that night.

That night Joshua sent about 5,000 men to lie in ambush between Bethel and Ai, on the west side of the town.

When the king of Ai saw the Israelites across the valley, he and all his army hurried out early in the morning and attacked the Israelites at a place overlooking the Jordan Valley. But he didn’t realize there was an ambush behind the town.

As soon as Joshua gave this signal, all the men in ambush jumped up from their position and poured into the town. They quickly captured it and set it on fire.