A substantial battle group from the Galactic Empire's naval forces, which included the Assertor, an Assertor-class Star Dreadnought, operated sometime following the Battle of Yavin in 0 BBY. This fleet was stationed along the boundary separating the Mid Rim Territories from the Outer Rim Territories to provide support for actions against the Alliance to Restore the Republic during the Galactic Civil War. It is believed that the battle group consisted of many starships, potentially dozens, featuring smaller dreadnoughts, Imperial I-class and Imperial II-class Star Destroyers, different cruiser-sized ships, and a variety of auxiliary vessels.
This battle group was referenced within Lead by Example, a sourcebook for the Star Wars Roleplaying game. Fantasy Flight Games released this book in 2016 for the Star Wars: Age of Rebellion roleplaying game.