Judges 1-2, Disobedience
Judges begins with Israel failing to obey God. They were instructed to wipe out the inhabitants of the land yet they took Adoni-bezek captive and humiliated him. This sets the tone for the entire book. Israel was not willing to carry through with the destruction of the Canaanites et al, so they were never to have peace nor were they able to have all the land that God wanted them to possess.