Book
The fictional events of the BattleTech universe constitute a "future history" that describes the course of humanity from modern times until the mid 32nd century. It can also be considered an alternate history distinct from our own, since its point of divergence from the real world occurs in the past; this is not the focus of the series, though, and is more the result of real-world history overtaking the early years of the BattleTech timeline.
Given its central theme of military conflict, the events of the BattleTech universe can be classed as a military history, albeit a fictional one. Incessant wars are the backdrop of most BattleTech stories and historical happenings, the majority of which concern individuals in the military rather than civilian sectors. Equally important to BattleTech history are politics and technology.