There are places in scripture that don’t seem as significant to us as it would to have been those it was initially written for. For example, if you were to read through the book of Exodus you will see that there are a few chapters where God is instructing them how to build the tabernacle and make their priestly gowns, then later in the book we see a few chapters where they followed through, and it is almost copy and paste of what we previously read. For a modern and casual reader this might seem redundant and arduous, but there is great significance to those passages being there. They show that the people did follow the exact commands of God and therefore the tabernacle is a legitimate place of worship for all who came their even hundreds of years later.
It is very much the same here, except the distance between proclamation and fulfillment is much longer. What we should see is that God always been faithful to his word. Here in the book of Joshua we have seen that God is faithful to the people of Israel and fulfilling promises made in the past. When we went through Genisis last year we saw that there was a promise given to Abraham that his descendants would come into the land of Canaan and make it their home. Now almost 500 years later he is doing exactly what he had promised he would do.
The people living out the manifested promise of God is what makes these war stories important to read about. These stories are about God being faithful to his promise and making sure that the people of Israel did come into the land that they were promised. Something to have the students do is to reflect on ways that God might have brought to fruition promises or prayers in their lives.