Joshua and Judges are both important books in the Bible, specifically in the old testament, because they reveal how God delivered the people of Israel from captivities and their conquest of the promised land i.e., the land of Canaan. Joshua is the sixth book of the old testament, and it tells the story of how Joshua after he was chosen by God, led the people of Israel to their promised land.
The stories of how they conquered the land of Canaan, and how they later fought themselves are all in the book of Joshua. Later in this book, the people of Israel were able to turn back to God with the instructions that they should be obedient to the law of Moses. On the other hand, Judges is the seventh book of the old testament, and it tells the stories of how God used some Prophets (judges) to deliver the people of Israel from their enemies.
After their conquest of the promised land, the Israelites would always do things contrary to the will of God, and God would always deliver them to their enemies until they repent.