I just finished Acacia: The War with the Mein by David Anthony Durham.

I didn't notice this until I was almost done this book, but Durham is also the author of Pride of Carthage, which I wrote about here. 

This book starts off slow, setting up a world run by a single empire that has been basically static for hundreds of years.  But one group that considers themselves oppressed has been plotting for most of that time and now strikes against the empire.

It's a complex story, because both sides are far from perfect.  The rebels are vicious and brutal, while the empire has been guilty of many terrible crimes, including slavery and drug dealing.  The main story really starts after the rebels have been successful and the heirs to the empire have been scattered to the countryside to rebuild and seek revenge.

Overall, well written and enjoyable.  It has the added advantage to telling a complete story even though it is obviously intended to be the first in a series.