Military science fiction
Military science fiction is a subset of
science fiction/
space opera where interstellar or interplanetary conflict and its (usually) armed solution make up the backdrop of the story. The
Star Wars movies [someone who has read the books please add them if you agree] could be considered part of this genre, while
Star Trek Voyager, which is more based on
compromise and
negotiation than
military action, would not.
A very popular series, and a recommended intro to this subgenre is David Weber's on-going Honor Harrington series, which comes with 'reasonably' logical technology, believable plot, and (disputed by some) outstanding character depth.
Another of the defining authors of the genre is David Drake, especially with his Hammer's Slammers series, but also with many of his other works.
Other examples: