Campaign:Band of Guardsmen

After three years of planetary siege, Perditus IX, the last world in which the Macharian Heresy persisted, is finally conquered: the last bastion of a forgotten conflict, that began nearly a millennia ago and that almost everyone else in the Galaxy belives to have ended several centuries ago.

Which is why this dirty, bloody and inglorious clean-up job was left to a bunch of regiments of the Guard just as near-forgotten as the conflict itself. Barely remembered by the Munitiorum and the red tape, barely supplied, barely acknowledged, virtually left stranded in the impossibly remote Halo Stars.

Now, the last fortress of the last Warlord of the Macharian Heresy is destroyed, and the ponderous bureaucracy of the Imperium slowly catches up. In the conflict, several dozen regiments from different worlds have seen action. With barely any reinforcement received in the last years, all these regiments ended up being enormously understrength, with some having barely a company left, some barely a few platoons.

Eventually, from the meanders of the Administratum, an order comes: Your efforts will be shortly required elsewhere. Your losses will not be reinforced. Instead, all the remaining Imperial Guard forces on Perditus IX are to be merged in a new Regiment, the "Perditus IX Mixed Regiment". The Guard Regiment founded farthest away from the Light of the Astronomican.

At that point, however, it probably doesn't even count as a Regiment anymore. It's just a bunch of people from the myriad different worlds of the Imperium, grouped together out of simple expedience and necessity.
A band of guardsmen.