Raven Guard - The Battle of Gate Forty-Two: It was the need to conduct war in a more conventional manner that led to one of the greatest setbacks in the XIXth Legion's history, and one that would foreshadow the terrible events at Istvaan V only a few years later.Soon after Horus was declared the Imperial Warmaster, the Raven Guard were recalled from operations along the coreward edge of the Ghoul Stars and ordered to take their place in the line alongside several other Legions under the Warmaster's direct command.The Aukum-Sothos Cluster had been brought to Imperial Compliance by the Luna Wolves in the opening years of the Great Crusade, but its people had fallen to a form of mass-psychosis and violently rejected unity with Terra. This unheralded secession was later determined to have been caused by xenos parasites which matured within the eye sockets of their hosts, in this case the unfortunate population of the cluster.As they matured, the parasites gained rudimentary control over their hosts and formed what amounted to a wholly alien, gestalt consciousness focused on a cabal of primary hosts dubbed the "Unsighted Kings." The newly ascended Warmaster Horus refused to see the cluster of worlds he himself had brought to Compliance slip from the Imperium's grip and so he vowed an Oath of Moment to reclaim its worlds no matter the cost.Horus had formulated a plan to cast down the Unsighted Kings in a lightning war that would purge the afflicted population while retaining the cluster's highly developed infrastructure for future re-population. Furthermore, a rapid victory would demonstrate to Horus' brother-Primarchs that the Emperor had been correct to elevate him so high a rank.The Warmaster's plan called for the bulk of four Legions -- the Luna Wolves, Space Wolves, Iron Warriors and Raven Guard -- to converge on the heavily fortified lair of the Unsighted Kings before a final, overwhelming assault was launched.Having brought the outer worlds of the cluster to heel in a matter of solar weeks, the Warmaster called a council of his brother-Primarchs, one part of his plan calling for the Raven Guard to make a frontal assault directly into the guns of the defenders of Gate Forty-Two.Corax argued against what he denounced as a waste of resources and a needless squandering of his warriors' lives, countering with a strategy of his own. The Raven Lord proposed that his Legion should draw off the enemy forces in a series of feints, allowing the three other Legions to overwhelm what defenders remained at the walls with comparative ease.In answer, Perturabo accused Corax of seeking to avoid battle, a crime verging on dereliction for a Primarch of the Legiones Astartes. The two very nearly came to blows, with only the intervention of Leman Russ staying bloodshed. The Wolf King counselled Corax to heed the words of the Primarch who the Emperor had set above his brothers.Russ urged Corax to smother his bitterness, but not to extinguish it, and allow that guttering flame to kindle the fire necessary to carry the battle through. Taking his leave of the council, Corax mustered the Raven Guard before Gate Forty-Two. Knowing their particular demeanour would carry them forward, Corax assigned many of his Terran-dominated companies to the vanguard, in particular those whose captains appeared the most willing to play their part in the Warmaster's plan.The assault that followed was hailed as the Legion's darkest hour, a grim honour that, tragically, would be displaced just a few Terran years later at Istvaan V. At the height of the battle, the assault companies decimated and the attack faltering in the face of overwhelming fire, Corax himself led the forlorn hope, his battle cry firing the XIXth Legion to such efforts that the breach was carried and Gate Forty-Two taken.The honour of slaying the Unsighted Kings was claimed by Horus as Warmaster and at the moment of their execution, the xenos' hold over the population was dispelled. The Akum-Sothos Cluster was delivered and the Warmaster's prize was reclaimed.The cost was terrible however, for not only had countless millions of hosts been crippled in mind and body, but thousands of Raven Guard, the bulk of them Terran-born, had given their lives before the shattered walls.Though the Battle of Gate Forty-Two was counted a victory by (and indeed for) Horus, its effects were far-reaching. The XIXth Legion was sorely depleted, leaving only 80,000 Legionaries under the Primarch's command and making it the smallest of the Legiones Astartes.Corax removed himself and his Legion from his brother's command, swearing bitterly never to serve alongside Horus again. One last consequence of the Battle of Gate Forty-Two lingers still. In its aftermath, those line officers who, before the coming of the Primarch, had served for so long under Horus' command were gone, and so the Warmaster was able to exert little in the way of influence over the Raven Lord's Legion.Many of these Terrans had been inducted into the Warrior Lodges, and with their deaths these unseen bodies all but vanished from the Raven Guard. It has been claimed by his detractors that in assigning the Terran-born Legionaries to the assault wave that would suffer the greatest losses, Corax did his Legion a service, consolidating his power and paving the way for a future more in line with his own vision.As a result, the Legion was largely spared the wave of insurrection that was later transmitted through so many of the Legions by the hidden auspices of the lodges.