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.
Judges 3, To Teach War
Having failed to follow God's commandments and destroy the inhabitants of the land, Israel would never fully enjoy peace. They intermarried, followed other gods and reaped the consequences. Since they would not know peace, God set them up to study war.
Judges 4-5, Deborah
The Canaanites held the fortress city of Hazor and controlled the Jezreel valley which was ideal chariot country. Israel was mostly dismounted infantry. So the problem was how to overcome the tactical advantage of Canaanite army. In this, God lent a hand by bringing rain.
Judges 6-7, Gideon
With Israel once again in apostasy, the Midianites spread across the Jezreel valley during the harvest. They plundered Israel's crops and oppressed her people. God called Gideon to drive the Midianites from the land.
Judges 8, Gideon's Pursuit
After driving the Midianites from the Jezreel valley, Gideon pursued them across the Jordan to finish the defeat. In that process he had to deal with two Israelite cities who refused to give him aid and with the tribe of Ephraim whose noses were out of joint.
Judges 9, Bramble Politics
After the death of Gideon, Abimelech, one of his sons by a concubine, conspired to murder the rest of his brothers in order to become king. His sole surviving brother gave an eloquent parable about a bramble bush becoming ruler over the trees. It is timeless and very much applicable to today.
Judges 10-12, Jephthah
The Ammonites revive a 300 year old land dispute with Israel and invade to enforce their claims. Israel persuades Jephthah to take command and drive them out. In that process, Jephthah makes an unwise vow, the result of which is that he had no descendants.