Joshua's Battle Strategies

Joshua secretly sent two spies to survey the land of Canaan, especially Jericho. So these men went to the house of a prostitute, Rahab. Apparently they were noticed, and someone warned the king of Jericho that it looked like spies were in the land. The king sent a message to Rahab warning her to bring the men out. Rahab took the men to the roof and hid them under stalks of flax. She then told the kings' men that she didn't know the men or know where they came from so she sent them away at dusk before the closing of the city gates. So the kings' men set out on a pursuit of the spies, falsely trailing them on the road leading to the fords of the Jordan river. As soon as the pursuers had gone out, the city gates were shut. Rahab told the spies:

"I know the Lord has given this land to you and a great fear has fallen on us. We have heard of how the Lord dried up the Red Sea for you when you came out of Egypt..."(Joshua 2:12). 

Illustration from a 15th-century French manuscript
of Josephus' Jewish Antiquities, 15th-century.

Because her house was built inside one of the city walls, Rahab used a rope to allow the men to lower themselves out of one of her windows to escape. She told them to run into the hills and hide for three days until the pursuers stopped looking for them. She asked that they show kindness (and mercy) to her and her family because she had shown kindness and helped them escape. They agreed to an oath with her. As long as she tied [a chord] of this rope of scarlet red in her window, and all her family remained inside her home, she and her family would be safe. But, they said, if the scarlet rope is not in your window, and your family is not in your home, then this oath is not binding.

Then they went to the hills and hid for three days before fording the river and returning back to Joshua. They told him everything that happened, and added,

"The Lord has surely given the whole land into our hands; all the people are melting in fear because of us" (v. 2:24).

This first story of the eventual conquest of Canaan falls in line with what some Bible scholars describe as a partial willingness (limited bloodshed) among the landless social class to help take the land away from the Egyptian governors of Canaan. A type of coup d'etat from within as many Canaanites embraced the faith of the Israelites and were willing "to come over to their side freely and willingly" (Barnes 361).

Stage of future battle.
The Israelites would cross from east to west, from the Moabite plains, across the Jordan River, before pausing at Gilgal, and then conquering Jericho.

Follow the Ark of the Covenant

In Joshua 3, the officers gave orders for the Israelites to follow the Ark of the Covenant and priests (Levites) who were carrying it, but they were warned to stay at a distance of at least 1000 yards away from it--"don't go near it!" And the Lord said to Joshua,

"Today I will begin to exalt you in the eyes of all Israel, so they will know that I am with you as I was with Moses."

The Lord then told Joshua to have twelve men, one from each tribe of Israel, to be ready. When the priests, who carry the Ark of the Covenant, reach the edge of the Jordan's waters, they will place their feet in the water. As soon as they do this, the flooding river waters flowing downstream will be cut off and cause the water to stand up in a heap. So the Israelites did as the Lord instructed Joshua, and they were all able to pass through. The priests even, who were carrying the Ark of the Covenant, stood firm on dry ground while standing in the middle of the Jordan river. When the people all passed through safely, the flood waters returned as before.

The twelve men (one from each tribe, chosen before) brought one stone each from the middle of the Jordan riverbed, where the Ark of the Covenant had passed through, and carried them over to the camp at Gilgal. They placed them there as a memorial for future generations, so they could remember and explain what the Lord, the God of Israel, had done for the Israelites as they passed through the Jordan river.

"He did this so that all the peoples of the earth might know that the hand of the Lord is powerful and so that you might always fear the Lord your God" (Joshua 4:24).

I found an interesting article about "gilgals" and the symbolism of an ancient stone memorial circle and wheel. Find it here.
And this blog is full of archaeological photos and explanations of what is thought to be an original site of this gilgal, but I can't verify the accuracy of that.
And another blog explaining this passage with a poem and link to a hymn. Very creative people online!