Fifth Bastion War

• Beginning: 1,192 ABY – Battle of Wayland
• End: 1,196 ABY – Invasion of Bescane
• Place: Manda'toma and Moffist Bastion
• Outcome: Stalemate; lingering animosity between both nations
• Major battles: See emboldened engagements below

Although the reasons for the conflict vary by source, with both the Moffists and Mandalorians attributing blame to the other, it is widely accepted that broader galactic conditions played a decisive role. Of particular importance was the Second Outer Rim Conflict, then being waged between the reformed Outer Rim Alliance and their allies against the Third Galactic Republic. This wider war destabilised many frontier sectors, particularly those bordering Manda'toma.

What is universally accepted regarding the outbreak of the fifth of the Bastion Wars is that Bastion initiated open hostilities. Grand Admiral Willem Stert, Supreme Commander of the Imperial Bastion Fleet, besieged the Wayland system with three Imperial VI-class Star Destroyers, among the most advanced warships of the era. In response, Manda'toma launched a counter-offensive, marking the first combat deployment of the Ge'tal sur'haii-class Mandalorian battleships. The siege was lifted narrowly, forcing Bastion forces to withdraw.

This engagement formed part of Stert's broader strategy. By presenting the appearance of an assault on Manda'toma's western fringes, he lured Mandalorian leadership into committing their fleet prematurely. Believing Bastion intended to strike Taris, Mandalore the Provider led a massive force toward the ecumenopolis, encountering only a minor Imperial detachment that disengaged after a brief clash. This manoeuvre left Mandalore itself exposed to a devastating assault by Bastion's main fleet, commanded by Stert's subordinate, Admiral Stellos Geldair.

The Sacking of Mandalore was catastrophic but short-lived. While the planet was not held, the attack inflicted severe infrastructural and psychological damage, allowing Bastion forces to regroup for the next phase of their campaign. With reinforcements arriving from Bastion, Geldair was tasked with the destruction of the Horuz shipyards, while Stert targeted the industrial world of Ciutric. The latter rapidly became the primary flashpoint of the war, which would continue for a further four years.

Mandalorian forces successfully reclaimed the Horuz system, though much of the shipyard complex had already been destroyed. Their subsequent counteroffensive against the Occupation of Ciutric, however, failed. Stert maintained orbital dominance while prosecuting a prolonged ground war against remaining Mandalorian defenders, repelling repeated attempts to dislodge his fleet.

Bastion consolidated its gains across the northern reaches of Manda'toma, fortifying Akuria, Corvis Minor, and Ciutric, the latter becoming the principal Imperial base of operations. Despite these successes, Bastion encountered sustained resistance from the Mandalorian Knights, a Force-sensitive sect devoted to Mandalorian traditions and based on Ciutric. Their actions posed persistent challenges to Stert's campaign.

Following a series of raids on the Mandalorian-held world of Myrkr, Stert deployed ysalamiri in operational theatres, negating the Knights' Force advantages. This adaptation enabled several successful Imperial defensive actions and contributed to Bastion's continued hold over Ciutric.

What became known as the Taris Campaigns saw repeated shifts in control of the ecumenopolis, with Bastion and Mandalorian forces alternately occupying the world. Eventually, Mandalorian forces succeeded in reclaiming and holding Taris, forcing Imperial units to retreat deeper into Bastion space.

Upon identifying Bastion's reliance on Myrkr, Mandalorian forces established a blockade that Imperial fleets were unable to break. This was followed by a Mandalorian victory at Shaum Hii, yet the broader strategic situation remained deadlocked, with Manda'toma deeply divided and neither side achieving decisive momentum.

In an all-or-nothing manoeuvre aligned with Mandalorian martial philosophy, plans were drawn up for the Invasion of Bescane. Nearly the entirety of Mandalorian military strength was consolidated into a single assault force aimed at Bastion's second planet. The operation succeeded beyond expectations, aided not only by the size of the Mandalorian fleet but by wider political developments.

In the aftermath of the Second Outer Rim Conflict, a large contingent of Mandalorian Exiles launched an attack on a Bastion fringe world. Fearing this action signalled the beginning of a broader, unquantified invasion, Bastion leadership reacted defensively. Under pressure from the Council of Moffs, Grand Moff Valavai Tarses ordered all non-occupation forces to withdraw into Imperial space.

The Defence of Dubrillion successfully repelled the Exiles, but the redeployment left Bastion unable to retain Akuria and Corvis Minor, both of which quickly rebelled. Bescane, however, remained under Mandalorian control.

The conflict demonstrated that, while Bastion possessed formidable military power, it lacked the willingness to sustain catastrophic losses. Imperial leadership soon pressed for a ceasefire, bringing an end to a war that had yielded little beyond entrenched hostility. The Fifth Bastion War resulted in immense casualties on both sides and inflicted lasting damage upon the populations and armed forces of both Bastion and Manda'toma.