The Siege of Trinumvira, or alternately known as the Defense of the Vira Bluffs Yards and Base, was a protracted, three-month-long attempt by the forces of the Galactic Empire to oust a mixed, but sizable force of Caspian defenders from their base in the Vira Bluffs and thereby secure control of the Union's capital world of Caspar. The battle represents the central focal point and essence of the Caspian Annexation Campaign, and is regarded as one of the most grievous, atrocious ground battles in its time, on par with the Battle of Mygeeto and the Battle of Hoth.