I liked that too, keep meaning to read the rest of the series.
That’s another David Weber book, the first in his Empire From the Ashes trilogy. Mutineer’s Moon happens to be available for download at the Baen Free Library, by the way. Along with some of the other Weber books mentioned in this thread.
And the second book in the trilogy has all the action you could ask for: huge space battles, noble sacrifices, overwhelming odds, neat weapons, sentient planetoids…you name it.
If you haven’t read his The Moon is a Harsh Mistress, go do so now.
Couple of mentions of Harry Harrison here, so I’ll throw out another: The Stainless Steel Rat series. Plenty of futuristic pulpy action, with a wicked sense of humor to boot.
The Sten series is also a good action/intrigue sci-fi series.
Military science fiction is a genre I read quite a lot of. I think I’ve read most of the stuff mentioned.
Try the Succession “series” by Scott Westerfeld. It’s pretty “hard” sci-fi with no FTL and relativistic time dilation is a bit of a cultural problem with ship crews. No real “magical” high tech, but some very well thought out ideas on advanced weaponry and technology. It’s not much of a series, just two books.
The Golden Globe, by John Varley
The space battles in Dread Empire’s Fall are amazing.
And if you like The Stainless Steel Rat, don’t miss the Bill the Galactic Hero books, also by Harry Harrison.
eta - Harrison only wrote the first of the series - several writers added thier own offerings in the next five books
The Saga of Pliocene Exile, starting with The Many-Colored Land, by Julian May.
Also I’m a big fan of the Vorkosigan novels–no surprise, considering I call myself Dendarii Dame!
…fleets of Death Stars fighting each other…
Oh frack! I forgot the Starfire books. Exactly what the OP is looking for.