Today's reading is Judges 1-2 (read it in the KJV or NIV)
Today's passage covers conquests of some remaining lands; lands still unconquered; the angel of the Lord at Bokim; and God's punishment of the Israelites for their disobedience.
The first books of Judges pick up where Joshua left off: with the Israelites controlling most, but not all, of the Canaanite lands. Unfortunately for the Israelites, "not all" seems to be the operative words in the previous sentence.
Judges 1 begins with the tribes of Judah and Simeon banding together to conquer some of the neighbouring, non-Israelite territories. (Judg. 1:1-8, 17-18) Together they kill 10,000 Canaanites and Perizzites at Bezek, cut off the thumbs and big toes of Bezek's king, and burn down the city of Jerusalem. The chapter also reminds us of Caleb's conquest of Hebron and Othniel's conquest of Debir, both located in the lands of Judah. (Judg. 1:9-16) The children of Joseph also manage to conquer a few of the remaining natives at Bethel. (Judg. 22-26)
Here things begin to go downhill. Judges 1 also includes a long list of territories the Israelites were not able to conquer: lands in the regions of Benjamin (Judg. 1:19-21), Manasseh (27-28), Ephraim (29), Zebulun (30), Asher (31-32), and Naphtali (34). In Dan, things were so bad that the Israelites of that tribe were forced to live in the mountains, because the Amorites in the valley were too strong for them. (Judg. 1:34-36)
Obviously, these unconquered lands are a problem. God promised the patriarchs and Moses that the Israelites would conquer all the lands of Canaan, not just most of them. How can God reconcile these unconquered lands with his promises?
The answer, which will be repeated throughout the Bible, is that it's the Israelites' fault. God accuses the Israelites of making covenants with the native pagans and following their gods. For this, he tells the Israelites that he will not drive out the remaining nations, but they will be "thorns in your sides." (Judg. 2:1-3, KJV)
When the generation who took part in the initial conquest died and was replaced by their children and grandchildren, things got even worse. These descendants openly worshipped Baal and Ashtaroth, Canaanite gods. (Judg. 2:10-14) At this point, God moves from merely allowing the other nations to persist in Canaan to using them against the Israelites. The pagan nations defeated the Israelites in battles because God was against them. (Judg. 2:15)
Among other things, this is quite a tidy solution for later Israelite theologians. Why didn't the Israelites defeat all the Canaanites? Because they were unfaithful to God. Why were the Israelites defeated in battle? Because they were unfaithful to God. The problem isn't with God, but with the Israelites. If only the Israelites had been more steadfast, more faithful, more loyal, they would have conquered the whole land.
This is a theme that has appeared before and will appear again many times. The Israelites complain or disobey God and some natural disaster or enemy army kills many of them. I have theorized before that the "Israelites were disobedient" line was really just an after-the-fact justification for natural disasters or defeats. When some terrible thing happened to the Israelites, they hunted for a reason and found one in some sort of disobedience. In a population of over six hundred thousand, surely someone was acting against God. In the case of the defeat at Ai (Josh. 7), the perpetrator was a single man: Achan. Once the Israelites settled down into their inheritances, there must surely have been all the sorts of problems we associate with a settled people: incursions from without, dissension from within, and natural disasters, to name a few. When hunting for reasons for these problems, no doubt the Israelites (or at least, their chroniclers) turned to their old standby reason, "we were unfaithful to God."
The entire book of Judges is an attempt to stem this disobedience. Whenever the people turned away from God, he sent them a judge to reform them. For a while, these reforms worked and people heeded the judges. But as soon as the judge died, the Israelites returned to their corrupt ways, were punished again, and needed another judge to reform them. (Judg. 2:16-19)
From the time they left Egypt, it seems like the Israelites have required a strong, firm leader. Similar to many modern nations, the Israelites become petty and selfish when left to their own devices. As we shall see through the book of Judges, the judges that God raises try to counterbalance this trend, often with mixed results.