The Indomitable, a Majestic-class heavy cruiser, functioned as the command ship for Task Force Aster within the New Republic's Fifth Battle Group. It saw action in the campaign against the forces of Zsinj. Later, it participated in both the Battle of Doornik-319 and the Battle of ILC-905 during the tumultuous period of the Black Fleet Crisis.
Commodore Brand, who also commanded the task force, directly oversaw the Indomitable. Captain Theb Tobbra held the position of first officer, while Lieutenant Threld served as a member of the ship's bridge crew. The vessel's complement of starfighters included E-wings from the 16th Fighter Squadron and K-wings belonging to the 24th Bombardment Squadron.
The Black Fleet Crisis FAQ on the website of author Michael P. Kube-McDowell originally established the Indomitable's identity as a Majestic-class heavy cruiser. Within the trilogy itself, the ship is initially referred to as a "star cruiser" in Shield of Lies, and subsequently simply as a "cruiser." This information was later corroborated by The Complete Star Wars Encyclopedia.