The promise of victory is given before the battle is begun; instructions/strategy are laid out for Joshua, and he will pass it on the people of Israel.
The instructions are an expression of Israel’s faith that GOD is in their midst and will provide victory. Just as with the wilderness wanderings, the coming of victory will happen His way, which is rarely (if ever) according to conventional human thinking. For instance, usually an attacking army would make some sort of war cry to intimidate the enemy. This time, however, the only sound(s) made until the seventh day will be the blowing of the priests’ horns and the tramping of feet in the army.
For the first six days, Israel undertakes what must have looked like (to the inhabitants of Jericho) a ridiculous endeavor – marching around the city with the entire camp of Israel – bot strong and weak – around him and the Ark. The action, however, is FAR from empty; 6 is the number of fallen humanity, falling short of GOD’s perfection. This translates to Israel’s inability to achieve victory without the LORD.
On the seventh day, Israel makes the expected circuit, but this time there are seven laps instead of the (perhaps expected) one. 7 is the number of completion, and added to the previous 6 days of marching makes a total of 13 – the number of tribes in Israel (Joseph’s two and the other 11 sons). At the end of the march, Israel is given the signal to SHOUT (drawn from the Hebrew “shabach,” one of seven Hebrew words for praise). At the sound of praise, GOD knocks down the otherwise impassible fortifications, also creating a ramp for Israel to enter the city with ease.
The only section of wall that does NOT fall down is the portion that held Rahab’s house. Having been faithful to the pact made with the spies in chapter 2, she has gathered her whole family with her, trusting in Israel’s promise to spare them all. Indeed, Rahab and her clan will be the only survivors of Jericho, becoming part of Israel – and Rahab in particular will be the second of four women mentioned in the ancestry of Jesus (Matthew 1)!