Joshua led Israel through 5 years of war against the people of Canaan. God commanded that the entire population of these irredeemably corrupt societies by destroyed. Joshua obeyed. In all Israel took 31 cities (Joshua 12:24) and smaller communities in rural areas. I would estimate that Israel killed well over 300,000 people in the conquest, but suffered very few combat casualties. Not all the inhabitants were destroyed. Many escaped into the mountains of the promised land or into neighboring areas. The Gibeonites made the sneaky treaty to enslave themselves instead of fighting. These pagan influences were not wiped out as God commanded and this will cause future problems for Israel.
Joshua was getting old ( he also lived through the 40 years in the desert). Caleb, Joshua’s only peer was 85. Everyone was tired. God gave them peace and let them divide the land between the tribes, although those tribes that got the areas that still had pagan remnants were assigned the duties of “mopping up” their own areas.