Lokan Crusade

The Lokan Crusade was a major joint-Imperial Crusade undertaken by the Jonmarines Space Marine Chapter several allies from the Imperium's various military forces against the Forces of Chaos.

History
The Lokan Crusade and the ensuing defence of Fulcana and Airtha, two major worlds in the Lokus Sector, was, contrary to the Reconstruction, another tragic event in the history of the Jonmarines, with the goal of recovering more knowledge on truth of the chapter’s history, the Jonmarines fleet, as proposed by the suddenly discovered Malakim Phoros of the Lamenters chapter, went to the Lokus sector to confront Inquisitor Tuplov in her role within the creation of the chapter. However, their arrival into the system almost caused a conflict between the chapter and elements of the Imperial Fists and Red Scorpions against the Knights Celestial and the elements of the Mantis Warriors and Lamenters, hostilities almost became violent between the Knights Celestial and Jonmarines when the Knights’ 5th company captain Xinor Jan was, having been sent to assess what exactly had entered their system, assassinated onboard the Jonmarine flagship, the Lawsundan Avengement, by an alpha legionnaire agent that had stowed away aboard one of the Jonmarines’ ships during the Howling Dark, in an attempt to unsettle and plunge the system into an internal war before a splinter of the chaos fleet spearheaded by the Malalites Reborn and their so-called “Tenth Pentagonal Alliance” could launch their assault on the system.

The resulting conflict caused the destruction of the Knights’ home world of Fulcana and the vast majority of the Knights Celestial chapter, half the chapter reported as missing in action after being lead by their chapter master to the defence of Airtha, while the rest were killed in action or presumed killed in action on Fulcana, their homeworld. The forces of the Lamenters and Jonmarines managed to withdraw and evacuate a large amount of the populace before the dark intentions of the Tenth Pentagonal Alliance could be revealed in the form of the Cicatrix Maeldictum tearing through and engulfing the sector. The fleets of the Imperial Fists, Red Scorpions and the Mechanicum stationed within Lokus were able to withdraw after suffering heavy losses, and fell back to the galactic centre to return to Terra and Mars respectively. The Bell of Lost Souls on Terra only had to chime for death of one chapter due to the incredibly lucky timing of the Jonmarines’ arrival.