The Inexpugnable-class tactical command ship, a sizable warship utilized by the Republic Navy during the Mandalorian Wars, was a notable class. These vessels, conceptualized and built by Rendili Hyperworks in conjunction with Rendili/Vanjervalis Drive Yards, functioned as both flagships and command ships. Often likened to a mobile space station due to its expansive 3,100 meters diameter, the Inexpugnable-class represented one of the largest spacecraft in the Republic arsenal during that time. These warships engaged in numerous conflicts throughout the Mandalorian Wars, notably including the Battle of Serroco. The Inexpugnable-class gained fame for its leadership capabilities within massive Republic fleets, employing sophisticated command strategies such as the Vanjervalis Chain to simultaneously oversee up to sixty-four Hammerhead-class cruisers. Despite its value as a fleet command vessel, inherent weaknesses limited its production run to only six ships. One such vessel, the Courageous, met its demise in early 3963 BBY, shortly after the Republic became embroiled in the Mandalorian Wars. The Centurion-class battlecruiser superseded them as the Republic's primary command vessel before the end of the Mandalorian Wars.
The disc-shaped Inexpugnable-class tactical command ship featured a central opening. Its considerable size, with a diameter of 3,100 meters, led to frequent comparisons to a mobile space station. The bridge showcased an innovative design, utilizing holograms projected onto a transparent deck to blend electronic and visual data for enhanced command capabilities. This bridge layout, humorously dubbed the "wishing well" by Republic helmsmen, occasionally induced vertigo. Operating the Inexpugnable-class required a crew of 4,300 Republic officers and enlisted personnel, in addition to carrying 2,000 troops. The class possessed a cargo capacity of up to 50,000 metric tons and sufficient supplies to sustain optimal ship and crew operations for a duration of two years.
Inexpugnable-class vessels were armed with five double turbolaser batteries, five light turbolaser batteries, two point-defense laser cannon batteries, and two tractor beam batteries. Three turbolaser batteries were positioned on each side of the main circular structure, with two more located near the vessel's bridge. Propulsion for the Inexpugnable-class was provided by four substantial thrusters powered by engines situated deep within the circular superstructure. For faster-than-light travel, the ship was equipped with a Class 2 hyperdrive and a Class 10 hyperdrive as a backup system.
The warship incorporated sizable hangars and a command center situated beneath the main superstructure, towards the stern. Further hangar decks were located on the vessel's bow, facilitating the rapid deployment of fighters from multiple levels. Adjacent to the fighter decks was a cargo bay located near the ship's brig. The class had the capacity to carry 144 Aurek-class tactical strikefighters and twenty-four S-250 Chela-class starfighters. The ship could also accommodate smaller transports, specifically twenty-four Conductor-class landing craft and six Ministry-class orbital shuttles. Furthermore, its hangar bays could support a variety of Republic support ships.
Within the Republic Navy, the Inexpugnable-class functioned as a command ship. Rendili Hyperworks and Rendili/Vanjervalis Drive Yards engineered it with the strategic intent of boosting sales of Hammerhead-class cruisers to the Republic. The Mandalorian Wars brought weapons coordination to the forefront of Republic tactical concerns, as numerous Hammerhead-class cruisers commonly defended Republic lines. The Inexpugnable-class was therefore equipped with an advanced sensor suite and a ground-breaking bridge design, enabling a flag officer to effectively command a fleet of up to sixty-four Hammerhead-class cruisers concurrently. While the Inexpugnable-class's ample hangar bays facilitated the swift deployment of fighter squadrons, they also rendered the ship susceptible to ramming attacks and boarding actions. The Centurion-class battlecruiser, a smaller vessel, eventually assumed the role of command ship.
Before the Republic became involved in the Mandalorian Wars, the Republic identified a need for a tactical command ship to manage the large fleets of Hammerhead-class ships protecting their territories. The Swiftsure, serving as a proof-of-concept, was constructed sometime prior to the Mandalorian Wars. Fewer than six Inexpugnable-class prototypes were built before the Mandalorian Wars began, designed by Rendili Hyperworks and launched from the Rendili/Vanjervalis Drive Yards on Corellia. This new class of command ships, costing an estimated 70,000,000 credits, effectively replaced the Republic's older command ships, such as the Reliance I. The Courageous was one of these prototypes. The Indefatigable and the Tremendous were also part of the production line. Republic crewmen affectionately called them "Inexies."
In 3964 BBY, the Mandalorian Wars reached the Republic when Mandalorian fleets launched attacks on Vanquo and Taris. During the Mandalorian Wars, Inexpugnable-class vessels served as large command ships and flagships for battle groups within the Republic Navy. The Courageous, under the command of then-Captain Saul Karath, led its battle group against the Mandalorians during the Battle of Vanquo. In early 3963 BBY, at Serroco, Zayne Carrick, the Jedi apprentice accused of the Padawan Massacre, experienced a powerful Force vision and subsequently stowed away aboard Lieutenant Carth Onasi's ship, the Conductor-class landing craft Deadweight, to warn Karath about an impending Mandalorian assault. However, Karath immediately recognized Carrick as a fugitive and imprisoned him within the Courageous's brig, disregarding the warning. As predicted, the Mandalorians attacked Serroco with significant force, employing nuclear missiles to devastate cities and Republic forces on the planet's surface. Following the attack, the Mandalorians boarded and seized the Courageous. Nevertheless, Karath, Carrick, and Onasi managed to escape, as Carrick had used the Force to dismantle the wall of his prison cell, granting them access to the Deadweight within the Courageous's landing bay. The Mandalorians repurposed the captured Courageous for their own use; Mandalore the Ultimate later declared that his battle-axe was crafted from the Courageous's hull. The surviving elements of the Courageous battle group merged with the Tremendous and its own battle group, while now-Admiral Karath transferred his command to the Swiftsure soon after the First Battle of Omonoth. The Diligence, captained by Dallan Morvis, was another Inexpugnable-class ship that saw service.
Following the Battle of Serroco, the remaining Inexpugnable-class ships, including the Swiftsure, the Tremendous, and the Indefatigable, received an updated sensor package that enabled the use of tactics such as the Vanjervalis Chain. This advanced sensor system linked the controls of up to sixty-four Hammerhead-class cruisers, predicted enemy movements, and optimized fleet positioning for maximum effectiveness. The manufacturers first fitted the Swiftsure with the system, making it the basis for the production model. Karath, commanding the Swiftsure, employed the Vanjervalis Chain to safeguard the Republic capital of Coruscant from any attack or infiltration, specifically to allow Republic and Jedi forces to intercept Carrick, whom the Jedi Covenant believed was planning to attack their operations on Coruscant. However, Haazen, the clandestine leader of the Jedi Covenant, gained control over all Republic ships linked to the Vanjervalis Chain. He had directed the Draay Trust to acquire Vanjervalis Systems and integrated fleet remote controls into his Sith artifact, the Gauntlet of Kressh the Younger. He then ordered Karath's fleet, including the Swiftsure, to attack the Republic strike team that threatened his plans. Haazen's Vindication, the Jedi Covenant's rebellion against the Jedi Order, was thwarted when Carrick and his former Master, Lucien Draay, recovered the Gauntlet of Kressh and used it to command the Swiftsure and the Republic fleet to fire upon both Haazen and the Draay Estate on Coruscant's surface.
Later that year, Karath led the Swiftsure and its task force to an asteroid field near Ithor. Anticipating a Mandalorian assault, the Swiftsure's fleet prepared to engage Cassus Fett, a prominent Mandalorian Field Marshal, and his forces. Fett's fleet engaged the Republic in a brief battle, but the attack was a diversion. Carrick and Fett—who owed Carrick a debt for warning the Mandalorians about the Rakghoul plague on Jebble—orchestrated the false attack on Republic forces to draw out the Crucible slaver ship Gladiator, which Carrick and his friend, Jarael, had previously encountered. Upon learning of the deception and its true purpose, Karath directed the Swiftsure's fleet to capture the Gladiator and its captain, Dace Golliard. Golliard revealed the location of Osadia, a key Crucible base of operations and where Jarael was being held captive, to the Republic. Karath then detached the Hammerhead-class cruiser Testament from his fleet to investigate, taking Carrick and his associate, Marn Hierogryph, along, with the objective of dismantling the Crucible and rescuing Jarael.
Due to design flaws, only six Inexpugnable-class vessels, including both prototypes and production models, were ever built. Production was halted, and the smaller Centurion-class battlecruiser took over the role of tactical command ship.
The Inexpugnable-class tactical command ship made its initial appearance in the eighth issue of the Knights of the Old Republic comic series. Along with other new Republic Navy starship classes featured in that issue and in the Days of Fear and Nights of Anger story arcs, the Inexpugnable-class appeared to share a design lineage with the Hammerhead-class cruiser.
The Inexpugnable-class exhibited a slightly different appearance in issue 31, where the command ship Swiftsure was depicted with a more pronounced keel and a smaller, rounder primary hull. This variation was partly due to artistic interpretation, and also because the Swiftsure was a proof-of-concept model.
Writer John Jackson Miller has stated that the names of Inexpugnable-class vessels were inspired by real-world naval ships. The Courageous is named after the French ship Courageux, whose design influenced the construction of four of Lord Horatio Nelson's Leviathan-class ships, a name also used for Admiral Saul Karath's own command ship in the Star Wars: Knights of the Old Republic video game. The Tremendous was also a British naval vessel during the Napoleonic Wars. The Royal Navy also included ships named Indefatigable and Swiftsure during the same period. The 2011 novel Knight Errant named the fifth Inexpugnable-class ship Diligence, while the sixth remains unnamed.