The main problem with space warfare is that the Sword-v-and-Shield paradigm is cranked up to 11 up there. Warfare in space would be INCREDIBLY wasteful in term of resources and, possible the worst of all, manpower. When you start slinging jets of metal plasma at relativistic speeds, armor becomes redundant. Resistance becomes futile. The one who shoots first win. Stationary positions (i.e. anything planetside, space stations, and anything in between) can be destroyed by pretty much anyone. Energy potential out of gravity wells and away from pesky atmospheres can be built up to ridiculous degrees.