Science fictional space warfare is main theme and central sub-genre of science fiction that can trace its roots back to classical times, and to the "future war" novels of the 19th century. With the Modern Age, directly with franchises as Star Wars and Star Trek, it's considered one of the most popular general sub-genres and themes of science fiction. An interplanetary, or more often an interstellar or intergalactic war, has become a staple plot device. Space warfare, represented in science fiction, has a predominant role, it's central theme and at the same time it's considered parent, overlapping genre of space opera, military science fiction and Space Western.