The Siege of Terra

No event in the long and bloody history of humanity looms larger than the Siege of Terra, the cataclysm that ended the Horus Heresy in the closing years of the 31st Millennium. For seven years the galaxy had burned as the Warmaster Horus, once the Emperor's best-loved son, turned half the Space Marine Legions against their father. Now the traitor fleets hung above mankind's birthworld, and the fate of the species would be decided beneath the ramparts of the Imperial Palace.

The Long Road to the Throneworld[edit]

Horus had launched his rebellion in the ash of Isstvan and carried it across the stars in a rising tide of betrayal. Rather than grind through every loyal world between himself and Terra, he gambled everything on a single decisive stroke: to seize the throneworld, cast down the Emperor, and deliver the galaxy to the Ruinous Powers he now served.

Breaking the defences of the Sol System was itself a war of terrible cost. Void fortresses were overwhelmed and the outer bastions fell, until at last the fleets of the traitor Legions drew into orbit above Terra. From their holds poured an army beyond counting: corrupted Astartes, daemon-things, and the war-engines of the Dark Mechanicum.

Rogal Dorn and the Ramparts of Humanity[edit]

The defence of the Palace had been entrusted to Rogal Dorn, primarch of the Imperial Fists and the greatest siege-master the Imperium ever produced. In the desperate months before the assault he transformed the sprawling wonder of the Palace into the mightiest fortress ever raised, its splendour stripped away for overlapping walls, gun-lines, and the layered void shields of the great Aegis.

Beside Dorn's Space Marines stood the golden ranks of the Adeptus Custodes, the Sisters of Silence, and countless millions of the Imperial Army. Yet no wall could hold forever against the numberless legions of Chaos, and Dorn knew it. His task was not to win, but to endure long enough for the Emperor's own designs to bear fruit.

The Storm Breaks[edit]

The assault opened with an orbital bombardment that boiled the sky and cracked the ancient mountains. Where Dorn was the master of defence, the traitor Perturabo and his Iron Warriors were the supreme artisans of the siege, and their guns ground at the walls without mercy. The traitors seized the towering Lion's Gate spaceport, opening a throat through which their heaviest engines poured onto the surface.

Titans strode through burning hive-cities, daemons spilled from tears in reality, and the outer districts drowned in slaughter. Loyalist counterattacks bought precious time in blood, among them a lightning raid by the White Scars that briefly wrested the spaceport back. Still the tide rose toward the heart of the Palace.

Blood at the Eternity Gate[edit]

At the innermost threshold, the Eternity Gate, the primarch Sanguinius of the Blood Angels held the line while the Emperor laboured within. Radiant and terrible, the winged Angel became the emblem of the defence, hurling back every horror even as exhaustion gnawed at his warriors. For a time, against all reason, the gate held.

Yet the defenders were being bled white, and the Warmaster's patience was not infinite. In an act still debated by Imperial scholars, Horus lowered the void shields of his flagship, the vast battleship Vengeful Spirit. Whether it was arrogance, a challenge, or one last flicker of buried regret, the invitation was unmistakable, and the Emperor chose to answer it.

The Duel Aboard the Vengeful Spirit[edit]

Gathering a small band of Custodians, the Emperor teleported onto the traitor flagship to end the war with his own hands. In the confusion Sanguinius reached Horus first and, refusing a final offer to turn traitor, threw himself upon the Warmaster. He was hopelessly outmatched by a being swollen with the power of the Dark Gods, and the Angel was struck down.

The Emperor found His favoured son gloating over Sanguinius's broken body. Even then He hesitated to destroy the child He had loved above all others, and that hesitation nearly doomed mankind, for Horus wounded Him again and again. Only when the Warmaster casually annihilated the soul of a loyal crewman did the Emperor grasp that nothing of his son remained. He unleashed his full and terrible might, burning Horus from existence body and spirit alike, so that Chaos could never reclaim him.

The Broken Master and the Golden Throne[edit]

When Rogal Dorn at last fought his way onto the flagship, he found the Emperor shattered, His body all but destroyed by the duel. The Master of Mankind was borne back to Terra and interred upon the Golden Throne, the arcane device that has sustained His ruined form for ten thousand years since.

With Horus dead the traitor host lost its will and was driven from Sol in the vengeful campaign known as the Great Scouring. Victory had been bought at a price beyond reckoning: Sanguinius slain, the Emperor entombed, and the dream of an enlightened humanity replaced forever by the grim Imperium of the 41st Millennium. The Siege ended the Heresy, but it also ended the age of hope.