Moshe reviews the events and lessons that they encountered and experienced in the desert.
Why does he go into great detail when discussing the more recent events, such as the battles they had just fought, which are probably still fresh in their minds, while the more distant events, such as events that they experienced 30 or 40 years ago, events whose details might no longer be so fresh in their minds, those he just mentions briefly. Why? Perhaps more time should be spent reviewing the older, more forgotten events?
Moshe's goal here was not just to review what they had experienced in the desert. Rather it was to teach them the lessons they would be required to glean as they are about to embark on a new life in a new country. The greatest of those lessons was the lesson mentioned in the last few psukim of Parshas D'varim - that they should know when they enter the Land of Israel that Hashem will always be there fighting their battles and protecting them.
That lesson is mostly derived from the more recent events, and therefore those are the ones Moshe dwelled on, for the most part.