Equerry is a bygone title, a relic of the Great Crusade era of early Imperial history in the late 30th and early 31st Millennia. Space Marines who were selected for the honour by a superior officer were known as Equerries, and served as a trusted comrade and a confidant to the senior officers of their Space Marine Legion. The highest honour was reserved for those Astartes selected to serve as Equerries to their Primarchs, the genetic forebears and masters of the Legiones Astartes. At the time, it was also customary for senior military officers from all corps of the Imperial Army to perform in a similar role by selecting a more junior officer as an aide-de-camp. By the late 41st Millennium, the practice had fallen out of favor, but some Astartes Chapters keep the tradition alive by assigning a personal Chapter Serf to each Battle-Brother. These modern Equerries no longer follow their master in battle, but function as a confidant and a link with their lost humanity for their Astartes master.
The tradition for more senior officers to take on an aide-de-camp, a junior officer who serves as assistant, close confidant and sometime factotum, predates the formation of the Imperium of Man as it existed on Terra since time immemorial. The first Space Marines, who had been genetically enhanced from basic Terran stock and who formed the core of the twenty Space Marine Legions of old, kept this tradition alive at the launch of the Great Crusade in ca. 800.M30, creating the title and position of Equerry. To be selected as the Equerry of a senior officer was an honour, and an opportunity to learn the ways of command from a renowned leader of the Legion.
When the Primarchs were rediscovered by the Imperium, most of them chose to perpetuate this tradition, and took an Equerry of their own, be it a trusted individual from their childhood on their homeworld, or a prominent or impressive Astartes of their Legion. This allowed some of the Primarchs to learn the traditions of their Legion while they imprinted their mark upon it, but more importantly, the Equerries served as counterpoint and foil for their master's decisions. As few Astartes would ever dare show hesitation or speak against one of the very sons of the Emperor, most Primarchs saw the wisdom of keeping one such bold individual at hand, a kinsman whose words of caution or alternative viewpoints could be more valuable than a thousand warriors once in the field.
After the Horus Heresy, the tradition of naming an Equerry fell into disuse amongst the Space Marine Chapters of the Adeptus Astartes. In th late 41st Millennium, the role of Equerry is often a secondary occupation of a Chapter or Company Champion. Tasked with defending his commanding officer with his life, fighting countless grueling battles back-to-back against all odds ensures that the Champion has a bonding sense of kinship with his company Captain or Chapter Master, which is usually reciprocated. Many Space Marine officers trust the word of their Champion as much as his sword to keep them alive.
Some Chapters have kept a variant of the title alive within their own traditions: they assign each Battle-Brother his own Equerry in the form of a personal Chapter Serf, whose role is to assist his master in all things and more importantly, grant him a tenuous but vital link with the great bulk of mortal humanity the Astartes warrior has left behind but is still sworn to protect. The Chapters who maintain this tradition are often those who pay the most attention to civilian casualties and collateral damage when prosecuting the Emperor's wars.
- Malcador the Sigillite - Although he never bore the title, Malcador effectively functioned as an Equerry to the Emperor Himself, being one of His true collaborators and friends and sharing His burden.
- Amon (Thousand Sons) - Amon served as Magnus' tutor before the arrival of the XVth Legion on Prospero, and he became one of the Legion's first Prosperine Astartes at the direct invitation of Magnus. Amon eventually rose through the ranks to become Captain of the 9th Fellowship. He became the founder of the Corvidae Cult and its first Magister Templi. He also served as Equerry to Magnus, responsible for the Primarch's security and for officiating certain sorcerous rituals, amongst other duties. Amon would not only survive the battles of the Great Crusade, but those of the Horus Heresy as well, eventually becoming a member of the Cabal of Ahriman and vanishing from recorded history after Ahriman's exile from the XVth Legion.
- Artellus Numeon (Salamanders) - Artellus Numeon was a Terran-born Astartes officer who served as the First Captain of the Salamanders Legion's elite 1st Company, known as the Firedrakes, throughout the Great Crusade and the Horus Heresy. He also served as Equerry to his Primarch and commanded Vulkan's elite personal Honour Guard, the Pyre Guard, which was comprised of seven Veteran Battle-Brothers of the Salamanders Legion.
- Khârn (World Eaters) - Centurion of the XIIth Legion's elite 8th Assault Company, Khârn was selected as Equerry by the Primarch Angron after nearly being beaten to death by the enraged son of the Emperor in the wake of his unwanted rescue from his homeworld of Nuceria. Despite this treatment, Khârn remained defiant, neither yielding nor begging mercy when he moved to convince his Primarch to give up his rage and accept his responsibility as the leader of the Legion that would become the World Eaters, proving his Legion's worth in Angron's eyes. Khârn ultimately was a poor choice as an Equerry, for instead of guiding and tempering his Primarch's words and decisions with balanced wisdom, he often was second into the thickest of the fray right behind him.
- Kor Phaeron (Word Bearers) - First Captain of the XVIIth Legion and spiritual counsellor and foster father to the Primarch Lorgar during hus youth on the Word Bearers' homeworld of Colchis, before Lorgar was rediscovered by the Imperium. It was Kor Phaeron's influence that corrupted his Primarch and the XVIIth Legion into repudiating their oaths to the Emperor of Mankind and becoming willing pawns of Chaos.
- Maloghurst "The Twisted" (Sons of Horus) - Equerry to the Warmaster Horus, Maloghurst served his master well and was brutally effective at the tasks of propaganda, spying and assassination which Horus set him to accomplish.
- Nathaniel Garro (Death Guard) - Battle-Captain Nathaniel Garro of the 7th Great Company of the Death Guard Legion was appointed as Equerry to his Primarch Mortarion on the eve of the Horus Heresy. Having been impressed more than once by Garro's resourcefulness and competence, it was Mortarion's hope that by promoting Garro to the position of Equerry and bringing him into prolonged contact with the Warmaster Horus, his Terran-born subordinate's unflinching loyalty to the Emperor of Mankind could be swayed, making him a valuable addition to the Traitor Legions' cause. This effort notably failed.
- Jago Sevatarion (Night Lords) - Jago Sevatarion, a native of Nostramo, served as equerry to Konrad Curze throughout the 30th and 31st Millenium. Serving as both First Captain of the Night Lords Legion and commander of the Atramentar, the elite Terminators of the VIIIth Legion's 1st Company, Sevatarion made his name known to all both before and during the Horus Heresy. It is thought that he met his unfortunate end during the Battle of Terra.
- Deathwatch: First Founding (RPG), pg. 106
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