Joshua was the right man for the job. After the Israelites had wandered for 40 years in a circular way through the desert, and God claimed the body of Moses, Joshua sent spies in to spy out the land, and especially Jericho. Joshua led the Israelites across the Jordon River, and entered Canaan from the East. This was definitely a tactical advantage, because of the distance from Philistine naval strength on the Mediterranean Sea. Then he miraclously won battles at Jericho and Ai.
The next city in the path of the Israelites was Gibeon. They resigned themselves to defeat, and tricked Joshua into making a treaty with them, so as not to suffer a certain defeat. From there, Joshua turns South and blazes a path of conquest through Canaan towards the Red Sea. All the Kings of the area tried to resist but he conquered them all with speedy marches and surprise attacks. This was an ingenious path, much like Sherman's later march to the Sea in Georgia in the Civil War. He effectively cut off the cities in the South from the cities in the North, and decimated them all one by one.
Word spread quick that a champion was on the march. Joshua's take over in the South spurred King Jabin of Hazor to recruit a massive army from the cities of the North to start a war with Joshua. But, Joshua's shock tactics demolished these armies as well. These victories were quick and decisive, but by no means total conquest. Small pockets of resistance had to be overcome with continuing guerilla warfare. These two campaigns were the foundation for the nation of Israel, but conquest was in no way complete by the time the book of Judges began.
The incomplete conquest of Canaan and the worship of foreign gods caused the young Israelite nation many problems in the time of the Judges. And, as you can see, they are still engaged in guerilla warfare today. The point of the story is that God had instructed them to conquer Canaan and totally drive out the inhabitants, which they never really did. The treaty with the Gibeonites should have never happened. And, they quit conquering way to soon. When Joshua died, his sword must have been buried with him.
God never intended for his children to be fighting small battles day by day. He meant for us to conquer and live victoriously. Christians are warriors. We were created to overcome this world, because we are the children of Light. John 12:36, Ephesians 5:8, 1 Thessalonians 5:5 Light always overcomes the darkness. John 1:5 says that the light of God shined in the darkness and the darkness could not overcome the light.
Joshua was more than likely born in slavery in Egypt. He was a young soldier under Moses when the spies first spied out Canaan and all but two returned with a bad report. These two, Joshua and Caleb were still around 40 years later to lead the armies of the living God into victorious battle. Moses may have been a Prince of Egypt (adopted) but Joshua was nothing more than a runaway slave, just like the other Israelites. There was nothing inside of these warriors that made them special beyond the power of God.
And, that my friend, is where you and I come into this picture. We are just like Joshua. We just need to unsheath our swords and take the land, for it is before us and God gives us the victory. Go ahead, take it... it's yours!