Event · M41–M42
Indomitus Crusade Fleet Quartus
Indomitus Crusade Fleet Quartus was one of the numbered battlefleets launched from Terra in 999.M41 as part of the Indomitus Crusade. Its formation followed the opening of the Cicatrix Maledictum, the Great Rift whose birth split the Imperium into the Imperium Sanctus and the Imperium Nihilus and left thousands of worlds isolated or under assault. Drawing on the first wave of Primaris Space Marines created under Archmagos Cawl’s Ultima Founding, and supported by Astra Militarum regiments and Imperial Navy squadrons, Fleet Quartus was mustered as one of several parallel commands answering directly to the crusade’s authority: Roboute Guilliman, newly returned to the Imperium and declared its Lord Commander. Where Fleet Primus operated under Guilliman’s own direct command, Fleet Quartus is recorded as having been assigned to reinforce and relieve Imperial holdings judged critical to the wider crusade’s cohesion, operating alongside the other numbered fleets that fanned out from Terra in the years following the Rift’s opening. Its campaigns fell within the broader Indomitus Crusade timeline of 999.M41 to 111.M42, a period in which newly reinforced Chapters delivered Primaris reinforcements to garrisons, broke sieges, and re-established the Astronomican’s reach across contested reaches of both Imperial halves. Accounts of its specific engagements are less fully attested than those of Guilliman’s own fleet, but its role fits the established pattern of Indomitus-era task forces: rapid reinforcement, chapter re-founding support, and the stabilisation of supply lines strained by the galaxy-wide crisis. The Indomitus Crusade was formally declared complete in 111.M42, though the conditions that had prompted it, chiefly the Great Rift’s persistence and the Imperium’s permanent division, did not resolve with it. Fleet Quartus’s forces, like those of its sister fleets, are understood to have been absorbed into the standing garrisons and ongoing campaigns of the Era Indomitus that followed, their Primaris strength folded into Chapters across both Imperial halves rather than maintained as a distinct crusade body. Its documented history remains anchored to Terra as the crusade’s point of origin and to Guilliman’s broader campaign, and it stands as one of the lesser-detailed threads within the larger, still-unfolding story of the Imperium’s response to the Cicatrix Maledictum.
See where Indomitus Crusade Fleet Quartus occurred on the galactic map in the 41st Millennium.