The outcome of the battle of Jericho is proof that God is in charge of this campaign. Joshua is given instructions and the people - perhaps having finally learned the lesson to obey and not complain? - seem to comply with every aspect of the plan.
Seven is an important biblical number, usually signifying completeness, and it figures largely here:
Seven priests, with
Seven trumpets of rams' horns shall lead the procession, marching around the city for
Seven days. On the
Seventh day, they shall march around the city
Seven times and then the people shouted and the walls fell.
Two other important instructions given to the warriors was to spare nothing devoted to destruction - all people and animals were to be killed, except for Rahab and her family in her house (vs. 17). Also, all gold, silver, bronze and iron was to be given to the Lord (vs. 18-19).