So the people shouted, and the trumpets were blown. As soon as the people heard the sound of the trumpet, the people shouted a great shout, and the wall fell down flat, so that the people went up into the city, every man straight before him, and they captured the city.
This is the tail end of the account of Israel conquering Jericho via miraculous means. After performing marches around the city, blowing trumpets, and keeping silent while they performed these actions every day for a week, the people are commanded to shout and the wall falls down, opening the city to be captured.
These actions are irrelevant to the actual falling of the wall, which is a miracle from God. But they had to perform them in order to show that they were following God's instructions and that God was the instrument of this miracle.
The tales of the miracles that had been performed in the recent past had preceded their arrival, and would continue to do so as they conquer therest of the land. Rahab, a prostitute, had heard of their God in this way and gave help to the spies of Israel in exchange for protection when they captured the city. The record is a little unclear here, but it seems she believed and began to follow God. Rahab is spoken of as faithful in the book of Hebrews in the New Testament.