|This article is about the Battle during the Horus Heresy, for the other Webway conflict see Webway War|
|Outcome||Stalemate. Imperial retreat, Webway portal sealed. End of the Imperial Webway Project|
|Imperium||Forces of Chaos|
| Emperor of Mankind
Ra Endymion (MIA)
The Archimandrite (KIA)
| Legio Custodes
3 Legio Ignatum Titans
| Daemon Hordes|
Sons of Horus
| Significant, including:
3 Legio Ignatum Titans
Following the attempt of Magnus the Red to warn the Emperor of Horus' treachery, catastrophe struck Terra. Magnus' psychic warning breached the wards the Emperor had placed around the Imperial Palace, causing the Golden Throne, a device intended to allow Human travel within the Webway, to malfunction. As the Golden Throne broke down, the Webway Portal deep within the Imperial Palace became breached. Floods of Daemons rushed through this breach, and the Emperor dispatched the Custodes and Sisters of Silence to hold the line and prevent Terra from being overrun. As the Custodes and Silent Sisterhood fought back immense Daemonic hordes, the Emperor sat upon the Golden Throne in a desperate attempt to stabilize the Webway Portal. Even the Emperor's psychic might was tested in this endeavor, and He became visibly exerted. The war within the Webway forced the Emperor's entire attention, leaving the waging of the simultaneous Horus Heresy to Malcador and Rogal Dorn. Malcador was the only one allowed to regularly visit with the Emperor.
Soon enough, the war within the webway fell into a pattern. The Custodians established a series of blockades across the tunnels within the webway. Behind these defended areas, the Mechanicum workers were repairing the damaged sections of tunnel and sealing the rifts to prevent more daemons from getting inside the webway. In front of the blockades, the Custodians and Sisters launched lightning-fast counter-attacks to keep the daemonic horde off-balance and prevent them massing in strength. Slowly, but surely, the Imperial forces were pushing the blockades forward as the pressure from the daemonic attacks waned. Nevertheless, some daemon assaults did manage to break through the Imperial defences and on those rare occasions the attackers wreaked havoc on the Imperial workers. More than once the daemonic entities were able to fight their way to the warp-gate of the Golden Throne. Desperate fighting ensued as the Custodians and Sisters doubled their efforts to throw back the daemons and prevent them surging through the warp-gate and into the Imperial Dungeon beyond.
As the war raged on, new troops appeared amongst the hordes of daemons attacking the Imperial forces. The powers of Chaos sent foully corrupted Chaos Space Marines, Titans and other war machines into the webway to try and force a victory. Mighty Greater Daemons including Bloodthirsters joined the battle as well. The sanctity of the Imperial Palace, the fate of the Imperium and the very life of the Emperor depended on the Custodian Guard and the Sisters of Silence. If they couldn't defeat the daemonic horde and its corrupted allies then Humanity was surely doomed.
The war within the Webway was waged for the next five years. Imperial forces were centered around the abandoned Eldar city of Calastar, known as the Impossible City, defending the Webway tunnels constructed by the Mechanicum and held together by the Emperor upon the Golden Throne. The Custodes were reduced by 90% and the Sisters suffered greatly as well. Two of the three commanding Custodes Tribunes were killed, leaving Ra Endymion as the primary Imperial officer. The Impossible City itself soon came under threat as a formidable new foe, Drach'nyen, appeared among the Daemonic hordes. Faced with this, the Custodes Diocletian Coros was charged with securing reinforcements from Terra. Due to the secrecy of the project, the scarce resources available because of the ongoing Heresy, the maddening effect of Chaos, and the questionable loyalty of the Legiones Astartes only the doomed prisoners of House Vyridion, the crippled Blood Angel Dominion Zephon, and Mechanicum Servitors and Skitarii were provided. A Mechanicum Dominus known as The Archimandrite was charged with leading them in the final defense of Calastar. Meanwhile, the Emperor charged the Sisters of Silence with the Unspoken Sanction, and the Black Ships worked at a hurried pace to gather Psykers across the galaxy.
In the siege of Calastar, the Custodes-led forces held back countless Chaotic hordes but the walls of the city were shattered by Warhound Titans of the Legio Audax. Brutal fighting for Calastar raged for weeks on end, the Custodes and Sisters not having a moments rest. As Daemonic, Traitor Legionnaire, and Chaos Titan hordes swarmed into Calastar, The Archimandrite ordered a general retreat of her forces. They intended to abandon to the Custodes and Sisters and instead secure the Webway route to Mars and reclaim their sacred homeland. This desperate treachery did not save The Archimandrite who was possessed by Drach'nyen, her gigantic mechanical form being used to attack the retreating Imperials. Calastar fell and the Chaos forces drove the Imperials all the way back to the Webway Gate leading to Terra itself.
It was at this moment that the Unspoken Sanction was completed on Terra. A thousand captured Psykers were sacrificed to power the Golden Throne without the Emperor. Free from His prison for a single day, He plunged into the Webway and appeared as a burning star before the Chaos hordes. The star shone with a golden psychic energy that forced the Daemons back, and the Emperor plunged into their ranks, reaping a terrible fury wherever He fought. The exhausted Custodes were reinvigorated by their master, fighting by their side. The Emperor summoned an army of loyal Imperial dead including Ferrus Manus that took the form of blazing avatars to fight the Daemons. Drach'nyen itself soon appeared, proclaiming itself the Emperor's end. However, the Master of Mankind was able to seal him into Custodian Ra Endymion, who was then ordered to run into the depths of the Webway.
The Emperor's actions gave the surviving Imperials enough time to evacuate the Webway, and as Chaos forces closed on the portal once more the Master of Mankind mounted the Golden Throne and sealed the gate. The gate would remain closed to the daemons for as long as the Emperor was able to power it from His throne atop the golden portal. Only the mightiest of psykers had power enough to do this and even then most would be exhausted and die in a short time. Only the Emperor had the might to keep the gate closed permanently and for Him the effort got harder as the Daemonic forces gathered about Him. For as long as the daemonic horde threatened to breach the portal, the Golden Throne would be His prison.
When the Emperor decided to confront Horus aboard the Vengeful Spirit, Malcador was left to maintain the Golden Throne and keep the portal closed in His place. After the injured body of the Emperor was brought back to the Golden Throne, the immense effort exerted by Malcador in keeping the portal shut had reduced him to mere dust. As the Emperor was placed back onto the Golden Throne, His body has allowed the portal to remain closed for the last 10,000 years. Should the Emperor die, the Imperial Palace would be breached and Terra itself would be overrun by Daemons.
- 1: Collected Visions pgs.326-330, 350-351
- 2: Deliverance Lost (Novel) Chapter 7
- 3: Master of Mankind (Novel)