Overview
Elysia is a comparatively pleasant world whose orbital piracy problem produced one of the Imperium's finest rapid-deployment traditions.
Its drop troops descend by grav-chute where slower armies cannot arrive at all, which makes the planet's tithe disproportionately valuable.
Pleasantness, in Imperial logic, is simply another resource to be taxed.
M41 and M42 status
Civilised world exporting elite drop regiments.
Saved from Chaos by the Custodes after the Rift; a recruiting world strained by Indomitus demand.
Timeline
Anti-piracy campaigns formalise Elysian rapid-insertion doctrine.
Drop regiments deploy across multiple Segmentum Solar emergencies.
Rift-era chaos multiplies requests for airborne response forces.
After the Great Rift opens, a Chaos Space Marine invasion of Elysia is thrown back by Captain-General Trajann Valoris and the Custodes Fury of Terra Shield Host.
Indomitus musters draw Elysian companies into crusade fleets.
Cartographic positions and several administrative details are intentionally approximate where published Warhammer sources conflict or provide no canonical coordinate system.