The War Council was the ancient military body convened by the Emperor of Mankind that aided the Emperor in guiding the course of the Great Crusade in the late 30th Millennium after the end of the Unification Wars. It was eventually replaced by the Council of Terra, and after the Horus Heresy, by the Senatorum Imperialis of the High Lords of Terra. The Emperor sat at the head of the War Council while the rest of the body was composed of the burgeoning Imperium of Man's greatest generals, talented administrators and the Fabricator-General of the Mechanicus of Mars. As the Great Crusade progressed and the lost Primarchs were reunited with their father, they too, were granted a seat on the Council, as was the Captain-General of the Legio Custodes. As the Great Crusade drew to a close in the early 31st Millennium, all the Primarchs were reunited with their Space Marine Legions and were busy completing the military campaigns required to prosecute the Great Crusade to its end. After the monumental victory of the Ullanor Crusade, the Emperor announced that he would be withdrawing from the Great Crusade to pursue secret endeavours on Terra that would benefit all Mankind, initiating his secret project to build an Imperial extension into the Eldar Webway. To direct the Great Crusade in the Emperor's absence, Horus Lupercal, first of the Primarchs and the most favoured son of the Emperor, was elevated to the esteemed rank of Imperial Warmaster. He was placed in charge of all the Emperor's military forces and charged with the completion of the Great Crusade. The War Council was dissolved not long before the start of the Horus Heresy and reformed as the Council of Terra, a civilian body without Primarch participation that was the precursor to the Senatorum Imperialis. The disbanding of the War Council in favour of the Council of Terra was one of the grievances that led several of the Primarchs to grow disenchanted with their father the Emperor, a grievance that would be exploited by Horus and the agents of the Chaos Gods to gain their allegiance to his attempt to overthrow the Emperor's rule.
After the end of the Unification Wars that had brought all of Terra under his control, the Emperor of Mankind convened the War Council to manage the execution of the Great Crusade. The War Council effectively became the true ruling body of the Imperium during the early and middle years of the Great Crusade. The Emperor Himself sat at the head of the Council; at his left hand was Malcador the Sigillite, perhaps the Emperor's greatest ally during the Wars of Unity and a psyker whose powers were matched only by those of the Emperor. The rest of the Council was composed of talented administrators drawn from the great ruling aristocratic dynasties of Terra and the Segmentum Solar, and when the Emperor forged his alliance with the Mechanicum of Mars in the Treaty of Mars, the Fabricator-General of the Mechanicus also claimed his seat. The War Council was also attended by the Paternova of the Navigator Houses. Supporting the council was a team of Astropaths who provided communication between the members since it became increasingly impractical for the group to physically assemble given the size of the growing Imperium and the inherent difficulties of travel through the Warp. As the Emperor left the homeworld of Mankind to lead the Great Crusade into the stars, he left the legendary Malcador to act as the Regent of Terra in his stead.
Newly Compliant worlds were given to the rule of Imperial Commanders who served as Planetary Governors, each of whom ruled, lived and died by the will of the Emperor and his War Council. Many of these new leaders were military men and women rewarded for their service by being given a planet to govern in the Emperor's name, while others were the indigenous rulers of worlds who had bent the knee to the Emperor willingly and had been rewarded for their wisdom. Imperial Commanders were masters of their worlds, but operated within the clearly defined strictures of Imperial law, and each possessed important responsibilities. First of all, they were to uphold and expand the sway of the atheistic, rationalist Imperial Truth upon the people of their new world, eradicating any vestiges of religious belief or superstition. Second, they were to supply troops and natural resources as called upon and provided shelter and succour for the Emperor's armies and fleets, enhancing the reach of the Great Crusade as it moved ever farther out into the galaxy. Importantly it was the responsibility of the Imperial Commanders to cleanse their population of grievous mutations -- specifically those individuals who were psykers. Each was told to expect great Black Ships to visit them and transport their psykers to Terra, and these ships were not to be denied access to the world's population of identified psykers upon pain of planetary extinction. This great endeavour was called the Imperial Tithe.
As the Great Crusade progressed, the War Council grew, as an inevitably widening vortex of admirals and commanders, generals, sector governors and ministers of state were appended to its administrative apparatus. Below these luminaries were advocates and technocrats responsible for the Imperial control of far-flung administrative systems and world-regimes with chains of supply and distribution whose scale beggared belief. As the years became decades, each of the Primarchs were discovered and brought into the Imperial fold and were given a seat on the Council, as was the Chief Custodian and Captain-General of the Legio Custodes, the Emperor's bodyguard. Yet, such men were creatures of war and not politics, and as some of the purely human Council members died in battle, or through simple old age or infirmity, they were replaced only irregularly. Malcador the Sigillite, unnaturally long-lived and razor-minded, proved the only individual capable of managing the minutiae of this vast Imperium, becoming over time both overseer of the Imperial Tithe as well as the Master of the Imperial Administration. So it was that the Imperium was increasingly coming under the control of its superhuman military components rather than the mortal men and women that the Emperor had sought to lift up to a new Golden Age through the Imperium's creation.
After the decisive victory during the Ullanor Crusade, when Mankind's re-ascension to predominance in the galaxy was no longer in doubt, the Emperor bestowed upon the Primarch Horus Lupercal the title of Imperial Warmaster and ceded to him control of all the Imperium's military forces in the Emperor's stead. The other Primarchs were then instructed to follow Horus and obey him and to complete the Great Crusade under his direction. There was, it is said, some disquiet among the Primarchs that the Emperor had decided to no longer fight alongside them, but the Emperor was as adamant as he was close-mouthed as to what he would do on his return to Terra. The Emperor then departed for the homeworld of Mankind and the dungeons deep beneath his great Imperial Palace to begin His great work under a veil of secrecy previously unknown in the Imperium. He drew to him certain advisors and retired to the private vaults of his city-fortress. While the Warmaster Horus directed the rest of the Primarchs in the resolution of the Great Crusade, the Emperor formed a new administrative body known as the Council of Terra. This formalised the role of the Emperor's previous advisors in the Imperial hierarchy and the Council began with a half dozen members. Already, under the far-seeing eyes of Malcador, the Adeptus Administratum had been born, a new civilian bureaucracy intended to govern the Imperium in place of military rule. It was a bright start for the new dawn of Mankind envisioned by the Emperor. This council, under the leadership of the Emperor, was to become the body of civilian government that would administrate the myriad bureaucratic tasks needed for the survival of the newly formed human interstellar empire. The Emperor was determined that in his Imperium power would reside with those men and women who were governed by its apparatus and not with an artificial military elite composed of genetically-engineered beings who were so powerful that they already possessed only a very tenuous grip upon their own humanity. The Primarchs and their Space Marines had been created to give life to the Emperor's dream of a united human Imperium stretching across the galaxy and to defend it from humanity's myriad foes. They were not to rule it as a hereditary caste of immortal warriors imposing their whims upon those they deemed mere "mortals" by brute force.
In addition to the Council of Terra, the Primarchs, under the Warmaster Horus, were to be a part of a separate Military Council, charged to lead the Imperium's military branches in the latter days of the Great Crusade and to spread the rule of the Imperium far across the galaxy. Yet the creation of the Council of Terra and a separate Military Council tasked solely with overseeing the Imperial military rather than the broader aspects of the Imperium became contentious. Some of the Primarchs took great exception to being ruled by those deemed less worthy of such honours than themselves. The Primarchs felt that it was they and their Astartes who had suffered and sacrificed the most to build the Imperium and thus it was they who should have the greatest say in how it was ruled, not a council composed of effete Terran nobles and faceless bureaucrats.
It is said that Horus himself was a staunch opponent of the Council of Terra's imposition of the Imperial Tithe, feeling that it would cause civil unrest and even outright rebellion in the more unstable areas of the Imperium as well as among some newly Compliant worlds. In time, this tension was one of the many growing resentments amongst the Imperial elite that allowed the Ruinous Powers to infect and corrupt several of the Primarchs, who had been dismayed that the Emperor would no longer be fighting at their side. Some, in their ignorance and hurt at the Emperor's refusal to reveal the nature of the secret project he had retired to Terra to complete, even whispered that they had been cast aside like tools whose usefulness had worn out. Such sources that survive from this ancient time, apocryphal as they are, claim that of all of the Primarchs, Angron of the World Eaters Legion was particularly bitter and most outspoken at this turn of events, not out of rancour for Horus' elevation above his brothers as the Warmaster, but rather as he counted this as the second time the Emperor had failed him, the first being when the Emperor had teleported him from his homeworld before he could lead his band of ex-gladiators in their final, hopeless battle against their oppressors.
Following the calamities of the Horus Heresy and the Emperor's interment within the Golden Throne and the sacrifice of Malcador, the Emperor could no longer take an active hand in ruling his realm directly. The role of Imperial Regent initially fell to Roboute Guilliman, the great Primarch of the Ultramarines Legion. It was he who set up the new ruling body for the Imperium based on the foundation of the Council of Terra, the Senatorum Imperialis, or as its members were more commonly called, the High Lords of Terra.
Known Members of the War Council
- Emperor of Mankind
- The 18 Primarchs
- Regent of Terra: Malcador the Sigillite
- Fabricator-General of the Martian Mechanicum: Kelbor-Hal
- Captain-General and Chief Custodian of the Legio Custodes: Constantin Valdor
- Master of the Adeptus Astra Telepathica
- Master of the Administratum
- Paternoval Envoy of the Navis Nobilite
- Horus Heresy: Collected Visions, pp. 15, 49, 92
- Imperial Armour - The Horus Heresy - Book One: Betrayal, pp. 22-23
- Warhammer 40,000: Rulebook (6th Edition), p. 403
- False Gods (Novel) by Graham McNeill, pp. 167-168