The book was written by Joshua, except for the end which may have been written by Phineas. The setting is about 1406 BC and the Israelites are about to cross the Jordan River into the Promised Land.
Joshua first shows up in Exodus 17:9 as Moses' aide. In Numbers 13:8 Moses is selecting a spy from each tribe and he selects Hoshea son of Nun. In verse 16 Moses changes his name to Joshua. Joshua & Caleb were the only two spies that came back with a positive report. Joshua served under Moses and was now called to be the leader of the Israelites. Joshua was 90 years old at this time. Joshua means "Jehovah saves" or "The Lord is salvation. Joshua corresponds with the New Testament name Jesus.
The book is divided into three sections: entering the Promised Land, conquering the Promised Land and dividing the Promised Land. The people entering the land are a new generation. There are great lessons in victory and living a victorious life in service to God. Because we are sojourners we are sometimes patient to the point of living as a prisoner of war.
Joshua is strong and courageous and goes on offense. Coming out of Egypt was one step, but crossing the Jordan was an entirely different step. Joshua was chosen for this task of leading God's people. Moses represented the law. From this side of the cross we know that righteousness wasn't found in the law, but the law brought us to the knowledge of our need for a savior. Moses (the law) could lead people to the promise but the law couldn't deliver. Yeshua (Joshua) led the people to the promise. For the sinful human (all of us; Romans 3:23) who understand their sin nature, there is a two part process; deliverance from the bondage of sin and receiving the promise. Entering the Promised Land was a life of warfare. While this was real people in a real life situation, we can also see our self modeled by the children of Israel. As Joshua is a type or model of Christ. We find our self looking at the Israelites and asking how they were so unfaithful. But, on closer inspection, we can actually see ourselves in similar struggles born of the sinful human heart.
The commander of the Lord's Army
The sin of Achan