Judges 3-5 explains that the Lord allowed some pagan nations to remain in the promised land in order to teach warfare to the generations of Israelites who had no experience in battle. Through this, the obedience of the Israelites would also be tested in whether they would hold fast to their own God and His commandments or accept the Pagan nations into their family and adopt their pagan customs and worship their gods. The Israelites failed and began to serve the images of Baal and the Asherah poles and God then allowed the Aram-naharaim King Cushan-rishathaim to enslave them for eight years. When the people returned to their Lord and cried out to Him for help, He sent a rescuer, Othniel. The Lord gave Othniel victory over King Cushan and there was peace in the land for 40 years. This pattern repeats several times more with Israel returning to evil ways and then the Lord allowing them to be defeated and oppressed by foreign Kings before they finally come back to Him and He delivers them once more.

Judges 2

"The LORD raised up judges... Yet the Israelites would not listen to their judges but prostituted themselves to other gods and worshiped them. Unlike their fathers, they quickly turned from the way in which their fathers had walked, the way of obedience to the LORD's commands. Whenever the LORD raised up a judge for them, He was with the judge and saved them out of the hands of their enemies as long as the judge lived; for the LORD had compassion on them as they groaned under those who oppressed and afflicted them. But when the judge died, the people returned to ways even more corrupt than those of their fathers, following other gods and serving and worshiping them. They refused to give up their evil practices and stubborn ways."

Judges
After the promised land was divided among the twelve tribes, each was responsible for driving out the remaining enemies from its own territory. In chapter 1, we read about some tribes that didn't drive out their enemies from their lands. For their disobedience, God withdrew His help in driving out the Canaanites and His blessing of the Israelites in battle.

Joshua 24
Joshua addressed the whole assembly of Israelite leaders, elders, judges, and officials, reminding them of their history regarding where they have been and have come from and all the events leading them to the promised land. Joshua reminded them of God's faithfulness, provision, protection, and keeping of His promises. Then Joshua said, "Now fear the LORD and serve him with all faithfulness. Throw away the gods your forefathers worshiped beyond the River and in Egypt, and serve the LORD. But if serving the LORD seems undesirable to you, then choose for yourselves this day whom you will serve, whether the gods your forefathers served beyond the River, or the gods of the Amorites, in whose land you are living. But as for me and my household, we will serve the LORD."

Joshua 23
Joshua addressed the leaders, elders, judges, and officials of Israel, saying "Be very strong; be careful to obey all that is written in the Book of the Law of Moses, without turning aside to the right or to the left. Do not associate with these nations that remain among you; do not invoke the names of their gods or swear by them. You must not serve them or bow down to them. But you are to hold fast to the LORD your God, as you have until now...You know with all your heart and soul that not one of all the good promises the LORD your God gave you has failed. Every promise has been fulfilled; not one has failed."

Joshua 22-
Before the Eastern tribes ( Reubenites, Gadites, Manassha half-tribe) had returned home, Joshua gathered them and blessed them saying, "You have done all that Moses the servant of the LORD commanded, and you have obeyed me in everything I commanded. For a long time now—to this very day—you have not deserted your brothers but have carried out the mission the LORD your God gave you. Now that the LORD your God has given your brothers rest as he promised, return to your homes in the land that Moses the servant of the LORD gave you on the other side of the Jordan. But be very careful to keep the commandment and the law that Moses the servant of the LORD gave you: to love the LORD your God, to walk in all his ways, to obey his commands, to hold fast to him and to serve him with all your heart and all your soul."
But, when they were leaving, the Eastern tribes built an alter near the Jordan and the Israelites thought they were breaking faith with the God of Israel and turning away for the Lord. The Israelites knew from past experiences that the wrath of God would be on the whole community of Israel, so the whole assembly of Israel gathered to go to war against them. But the Eastern tribes reassured the Israelites that they built the alter to the Lord and to witness before the generations to follow that they also have a share in the Lord.

Joshua 12-21
So the LORD gave Israel all the land he had sworn to give their forefathers, and they took possession of it and settled there. The LORD gave them rest on every side, just as he had sworn to their forefathers. Not one of their enemies withstood them; the LORD handed all their enemies over to them. Not one of all the LORD's good promises to the house of Israel failed; every one was fulfilled.