Judges 3 starts with what seems like a lot of repetition, but there's a bit more to it than that. The SAB says of verse 8 that God sold the Israelites into slavery "again". Actually, while this was mentioned in the previous chapter, this is the first time (unless you might want to count their time in Egypt, which isn't quite the same). As I said in my last post, the second chapter is more like a summary, so while it talks about some things that we see here, it's not talking about specific events, but rather the events of the book as a collective entity, which really start here.
And really, it's an odd turn of phrase that I don't quite parse. God certainly doesn't literally sell them into slavery, but the metaphor is surely implying something along those lines. God has nothing to gain by letting them go into slavery, but they've got a lot to lose, and it's largely their own choice for their disobedience.
So now the story returns to Othniel, Caleb's nephew. Apparently the story earlier about his unusual marriage was probably a setup for this later story, and the reason it was retold in Judges. Most of us have a modern perception of what a "judge" is, but in the context of this book, most of the judges of Israel were something akin to warrior-kings. They're people who have a certain degree of authority in their time, usually because of their ability to fight and protect their own people from enemies.
The deeper meaning of this is all a matter of perspective. The SAB calls the fact that God made Othniel into a great warrior unjust, violent and contradictory to the supposed nature of a God of peace. Well, I won't argue that war is not violent; it is by nature. But consider that the SAB says it's unjust to send the Israelites into slavery, and then immediately claims it to be unjust to redeem them. It seems like there ought to be only one claim of injustice here at most, take your pick. The problem is, when it comes to war, it seems unlikely that God is going to be on both sides at the same time. (I think it's likely in many cases that God is on neither side; I suspect that to be the case in our current war with Iraq, which happens to be in Mesopotamia.) Does a God of love go to war? I think He does if there is a loving reason to. Few people would argue that it was a bad thing to go to war to stop the Holocaust. When a situation deteriorates far enough, I think sometimes war is necessary to achieve peace. (Once again, I think there were good and noble reasons to institute a regime change in Iraq; I just didn't see the administration promoting any of those reasons. Justifying the war with false claims of WMDs is hardly noble. But enough editorializing, I've got to get back to that 3,000 year old Iraq War.) Indeed, the upshot of that war was 40 years of peace.
After that peace, there comes a time when they turn from God and the king of Moab takes them over. Eventually, God sends Ehud, who has a rather nasty scene of stabbing the king. The SAB labels it violent (again, I agree) and "language", which is less clear. The thing is, if you didn't already guess it, the phrase "the dirt came out" is the translators cleaning up a phrase that is unclear in meaning, but probably is referring to feces. Apparently, the king crapped his pants when he was stabbed, although a few other possible translations are out there.
Later, they end up killing 10,000 Moabites. This may seem violent and unjust, but once again, if you read it clearly, this is a squelching of a military invasion. Sure, there are a few times in this book when it seems that the killing is pretty arbitrary, but I don't think this is one of those times. This is a major battle that led to the ending of a war and a foreign occupation of the land of Israel. The SAB's page on Moab here has a couple errors, then, one of which unequivocally should be fixed (and now has been). So long as I'm there, I also think that the verse in Jeremiah is being understood wrongly as well. It's not a command, but an observation that Moab is about to be destroyed.
The chapter ends with a brief note about Shamgar, the third judge. All we know about this guy is that he killed a lot of Philistines, AND that he "delivered Israel". This may have also been an act of war in defense of his homeland, in which case I would not fault him personally. This is the first of several judges that are presented to us with minimal information, so one can only speculate.