Judg 2:10
After that whole generation had been gathered to their fathers, another generation grew up, who knew neither the LORD nor what he had done for Israel.

And whose fault was that? They had been given this admonition earlier.
Deut 4:9
Only be careful, and watch yourselves closely so that you do not forget the things your eyes have seen or let them slip from your heart as long as you live. Teach them to your children and to their children after them.

The people forgot what God had done for them. They neglected to teach it to their children. They prostituted themselves to other gods. Remember God’s relationship to His people is like a marriage. These people were God’s people. They had a covenant relationship with Him. To go after other gods for self-serving motives is to be a prostitute, which is what they did. Do you notice the correlation to what we do as Christians now? Don’t we prostitute ourselves when we value other pleasurable things above our worship of God?