This introduction to the book of Judges overlaps with the last few books of Joshua. It is as if the end of Joshua records the promise of occupying the land, and Judges records the failings of Israel in taking the same promises at face value. It is worth reading the two books together because they work together to tell a whole story.
Back to Judges … the faith and obedience of the 85-year-old Caleb and his family is in stark contrast with, for example, the way Judah treated King Adoni-bezek: rather than executing him (as ordered by God), they administered Canaanite justice, cut off his thumbs and toes, and let him live in Jerusalem, which, despite being the scene of at least one devastating battle, was regained by the Jebusites and stayed in their hands until King David successfully took it.
It must have been devastating for the Israelites when God told them the consequences of their disobedience in taking the land:
2:2-3 For your part, you were not to make any covenants with the people living in this land; instead, you were to destroy their altars. But you disobeyed my command. Why did you do this? So now I declare that I will no longer drive out the people living in your land. They will be thorns in your sides, and their gods will be a constant temptation to you.
In fact, they wept loudly and offered sacrifices. But it was too late. And it got worse:
2:10 After that generation died, another generation grew up who did not acknowledge the Lord or remember the mighty things he had done for Israel.
This was important. God rescued them from Egypt, kept them through the wilderness, teaching some hard object lessons along the way, and gave them this land on condition they obey Him.
2:16-19 Then the Lord raised up judges to rescue the Israelites from their attackers. … 19 But when the judge died, the people returned to their corrupt ways, behaving worse than those who had lived before them. They went after other gods, serving and worshiping them. And they refused to give up their evil practices and stubborn ways.
This exactly described the pattern of life around the first three judges: Othniel,Ehud and Shamgar.