The Physics of Space Battles. It won’t really be like the dogfights or naval style battles in our scifi books, movies and television shows.
In principle, yes, your enemy could come at you from any direction at all. In practice, though, [they] are going to do no such thing. At least, not until someone invents an FTL drive, and we can actually pop our battle fleets into existence anywhere near our enemies. The marauding space fleets are going to be governed by orbit dynamics — not just of their own ships in orbit around planets and suns, but those planets’ orbits. For the same reason that we have Space Shuttle launch delays, we’ll be able to tell exactly what trajectories our enemies could take between planets: the launch window.