The Dread Empire's Fall series is set in a future in which the powerful Shaa species has conquered humanity as well as several other intelligent species (several thousand years in the past relative to the time when the novels are set), imposing on them their inflexible set of laws known as "the Praxis". When the last living Shaa dies, the species they conquered first, the Naxids, attempts to appoint itself rulers of the former Shaa empire. A civil war erupts when the other species resist them, including the protagonists, Terran naval officers Caroline Sula and Gareth Martinez. Since the Shaa empire stopped expanding long ago and its military was largely occupied by training and suppressing the occasional mutiny or revolt, its strategic and tactical doctrines have become matters of rigid, unchanging tradition. To stop the Naxids, the other species must practice innovation and creativity, something the Shaa attempted to stamp out long ago.
At Tor.com, Jo Walton appreciated the trilogy comprised by the first three novels as very well-made, "funny and clever" conventional examples of their genre: "There's a war, in which the characters get to do clever things and get promoted. If you like military SF you'll like it."
The first three novels form a trilogy, while the later books are stand-alone works set after the events of the trilogy.