This is the first novel of Cherryh's Alliance/Union series.
Conrad Mazian's Company Fleet is losing an interstellar war with Union, due to lack of support from an oblivious Earth. Union is composed of breakaway colonies which use Azi (artificially born, second-class human beings who are given memories and training via "tape") to expand their population and economy, a practice abhorred by Earth and the merchanters (families who crew freighter starships).
In desperation, Mazian plots to both seize control of Earth's government and destroy enough key star stations between the two sides as to make it too costly for Union to continue waging war. All that remains to complete the latter step is Downbelow Station, orbiting Pell's World. Mazian takes over the station, and its leader, Angelo Konstantine, is killed. Damon, his son, goes into hiding with the help of Josh Talley, a memory-wiped POW dropped off at the station by Signy Mallory, one of Mazian's most senior captains. Through the efforts of these three, particularly Mallory, Mazian's coup d'etat fails, Downbelow Station is saved, and a third power is born when the merchanters unite.
Best part of story, including ending:
It's a well-thought-out space epic on a grand scale.
Best scene in story:
Probably my favorite is when Mallory takes the irrevocable step of mutinying against Mazian. That's when the fireworks start.
Opinion about the main character:
Mallory is fundamentally decent, but at the same time ruthless enough to do what has to be done.