I think it's interesting here to see how the Lord fights his battles with his nation. It's good parallels to how he also does so with our own difficulties in life.

One theme I like a lot is how it is often said that the Lord has already given you this land. The promises of the Lord are sure, he talks about them as if they were already fulfilled. To the armies of the Israelites, they are simply going in to claim the blessings, once they continue in their faithfulness.

• Joshua 1:13

A history of what nations were attacked, how, in what order.

See Deuteronomy 20 for the rules of going to war.

• Some kind of recon is done (Deuteronomy 20:1)
• There is a conference or set of sermons, and most likely covenants and rituals performed here by the priests, for the promise is made "the Lord your God is he that goeth with you, to fight for you against your enemies, to save you."
• Conditions at home given as exceptions for going to battle (house, vineyard, wife)
• Personal option given to those who do not want to go to war are excused

Then, once the army marches to battle,

• A proclamation of peace is offered, and if accepted, the nation will become tributaries
• If they refuse and make war, then create a siege (which is another attempt at a peaceful resolution)
• Then after the Lord gives them the city, slay the males
• Keep all the spoils
• Don't cut down the fruit trees, use the others for weapons of war

In the case of the Canaanites, exceptions are given where all is to be destroyed: Hittites, Amorites, Canaanites, Perizites, Hivites, Jesubites. The reason given is because of idolatry and their abominations, which has been the cause of the downfall of Israel itself for years.

Here's what happened as Moses prepared the company of Israel to enter Canaan, seeing how they match up with the commandments.

First, Moses sends spies into the land of Canaan, one from each tribe, to report on its condition (Numbers 13:1-3, 17-20).

• There is a conference upon their return, where the twelve spies give their report. (Numbers 13:26)
• During this time, Joshua and Caleb report that the Lord is able to win the battle. (Numbers 14:6-9)
• The congregation agrees to murder the two (Numbers 14:10)
• The Lord speaks to the Israelites, withdraws his promise to help them (Numbers 14:22-23)

Later, some Israelites try to go to battle on their own. They are warned not to, and those who try to attack the Canaanites are slain (Numbers 14:42-43).