There are 7 pages on our website that are tagged with military science fiction
Military is a huge subgenre, with its own specialized publications. Soldiers and warfare are central to these stories. Some are near-future, and depict humans fighting each other. Others span star systems and even whole galaxies, with vast ongoing conflicts with aliens. David Drake and Elizabeth Moon are masters of this field, while Joe Haldman's novel The Forever War will soon be filmed. David Feintuch's "Hope" novels essentially translate the 19th century's British Royal Navy into outer space. (Usually the humans and aliens are closely matched, lest it become a rather short "Bambi vs. Godzilla" type story.)
