"Through the artifice of the Martian priesthood were these warriors created. By the grace of the almighty Emperor are they given now to you. Silence your questions and instead rejoice at the honour done to you this day. You are handed the gift of hope by the immortal Master of Mankind Himself, and you will accept it with sincere and solemn gratitude lest you be taken for the traitors that you profess to hate."
The Emissaries Imperatus, known also as the "Heralds of the Golden Throne," is a Shield Host of the Adeptus Custodes, the stalwart guardians of the Emperor of Mankind. Since the ancient times of the Great Crusade, these Custodians have been charged with the sacred duty of acting as the personal messengers of the Master of Mankind.
Since the Emperor's internment in the Golden Throne, a small minority of Custodians believe they can hear the Emperor's voice calling to them during meditations, and believe that it is His hand that guides them to bear their master's sacred words across the galaxy to those Imperial commanders who are destined to hear them or bequeath some ancient relic from the palace vaults to a chosen champion.
In the days of the Great Crusade, the Emperor often entrusted crucial messages or artefacts to be borne by His Custodians. It is a duty they still fulfil now, speaking with the authority of the Master of Mankind himself.
Though the Emperor has long been confined to the Golden Throne, there are those amongst the Ten Thousand who claim to hear their master's voice during their meditations, and to feel His hand guiding them.
To their comrades there is no implication of divine intervention in this, for the Custodes have never viewed the Emperor as a god. They merely see their liege's indomitable will at work, reaching out from his shattered frame to direct His praetorians as He did when He could still walk amongst them.
Those who feel the Emperor's guidance the keenest become Emissaries Imperatus. They band together in like-minded groups and, through discussion and meditation, interpret what it is that the Master of Mankind wishes them to do.
With the tacit approval of the Captain-General of the Custodes, they bear the Emperor's words across the Imperium to commanders who must hear them, or occasionally unlock some ancient device from the palace vaults and bequeath it to whichever champion can wield it best.
For thousands of Terran years the Emissaries Imperatus have been seen abroad, but rarely and in small numbers. Yet with the return of Roboute Guilliman and the commencement of the Indomitus Crusade, their activity has increased considerably.
When the resurrected Primarch announced his intention to bear the secrets of the Primaris Space Marines to the Loyalist Firstborn Chapters, there was some resistance from the Adeptus Custodes, who feared strengthening those who might one day rebel against the Emperor once again.
Yet dozens of Emissaries Imperatus stepped forwards to intercede, stating this was the will of the Emperor. They accompanied Guilliman's Crusade, many of them taking to the air as Vertus Praetors, the quicker to deliver messages of reinforcement to the embattled Space Marines.
The presence of the Adeptus Custodes also ensured that even the most traditional Chapters accepted the Primaris warriors into their ranks. One does not decline a gift from the Emperor's own hand, after all.
Bringers of Greatness
In ca. 999.M41, the newly resurrected Roboute Guilliman, the re-installed Lord Commander of the Imperium, announced the Indomitus Crusade, a desperate and determined undertaking by a combined Imperial force to drive back the rampaging armies of Chaos following the fall of the Fortress World of Cadia and the formation of the galaxy-wide tear in reality known as the Great Rift.
As part of this crusade, the Ultramarines Primarch intended to bear his newly revealed project, the Primaris Space Marines, reinforcements and the secrets behind their creation to the far-flung and hard-pressed Space Marine Chapters. On the eve of his decision, a large number of Emissaries Imperatus stepped forwards, compelled by the spirit of the Emperor to accompany the crusade.
These were the envoys who brought Guilliman's gift to the Adeptus Astartes; their presence ensured that even those Chapters the Primarch did not visit in person understood the gravitas of what they were offered, and set aside whatever mistrust or conservatism they might have had in order to embrace the Emperor's beneficence in their hour of need.
- Codex: Adeptus Custodes (8th Edition), pp. 27, 32, 48