Right off the bat, he begins a review of Israelite history at Mt. Horeb (6), the mountain of God where he received the Ten Commandments.
Warning: Scholarly Disagreement Ahead! Many scholars believe that Horeb is another name for Mt. Sinai, while others think they were two different places.
Forget about all that, though. The important thing, story-wise, is that Moses is giving the commencement address to the Israelites. He's trying to give them a sense of perspective on their journey so far.
That's right, this whole thing is told from Moses's point of view.
Deuteronomy places the new nation of the Israelites at the edge of the Promised Land. God is about to fulfill the promises made to Abraham, Isaac, and Jacob back in Genesis, when he promised them innumerable offspring and a ton of land.
And don't forget—we know from the beginning that they'll have to take the land from the current inhabitants, among them the Canaanites and the Amorites.
The Israelites have been wandering through the wilderness for 40 years. They stop from time to time and make camp (who wants to move constantly in the burning hot desert?).
Along the journey, Moses realizes that he is unable to judge all of the disputes in the camp. (In Exodus, we're told that there are hundreds of thousands of Israelites. How would you approach judging all the disputes in a population of that size?)
So Moses appoints leaders over various sections of people and encourages them to be fair judges. Each of the twelve tribes of Israel gets its own judge. Looks like Moses was not only a great legislator, but also a great delegator (9-18).
Moses continues on to recount the failures of the previous generation of Israelites. That's right, we're in a new generation. After all, 40 years is a long time in a world when life expectancy was way lower than it is now.
Here's how it went down:
On the borders of Israel, twelve spies (one from each tribe—get used to this system) go into the Promised Land to check things out. Two of them, Joshua and Caleb, believe they can take the land, while the other ten incite fear in the people with tales of enormous castles and muscular opponents.
The Israelites don't trust in God (this isn't new) and wish that they could return to Egypt (19-33), where they'd been slaves.
God gets really annoyed about all this grumbling, and judges these Israelites for their lack of trust.
Now these people will not be allowed to enter the Promised Land; and for some unspecified reason, or maybe because God was just angry, Moses can't go into the land either.
God sentences the Israelites to roam the wilderness for forty years. Only Joshua and Caleb will enter the land with the next generation of Israelites. (34-40). Can't argue with experience.
The Israelites, ever fickle, change their mind and are now ready to fight the inhabitants of the Promised Land.
The Lord tells Moses to warn the people that he will not be with them.
But the Israelites saunter into the land anyway to try and stir up trouble. And—surprise, surprise—they are soundly beaten.
The Israelites return from their defeat and plead with the Lord to change his mind, but the Lord refuses (41-46). He's a tough sell.