The first city overthrown was Jericho. This city had very strong and high walls, and the Hebrews were not able to break them down. But the Lord could do what man could not.
One day Joshua saw a man near the camp, with a sword drawn in his hand. "And Joshua went unto him and said, Art thou for us or for our adversaries?
"And he said, Nay; but as Captain of the host of the Lord am I come." Joshua 5:13-15. Then Joshua knew that it was Jesus Christ, for He is the Captain of the Lord's host.
Joshua Commanding the Sun to Stand Still.
The Lord told Joshua what to do. Each day, for six days, all the army of Israel was to march around the city. The soldiers were to go ahead, the priests with the ark of God were to come next, and all the rest of the people were to follow.
On the seventh day they marched around the city seven times. "And it came to pass at the seventh time, when the priests blew with the trumpets, Joshua said unto the people, Shout; for the Lord hath given you the city." Joshua 6:16.
And when the people shouted, the walls of Jericho "fell down flat," and the soldiers went into the city and utterly destroyed it as the Lord had told them to do. This was to show to all nations that God was fighting for Israel.