Ganymede

Ganymede, known in the Era Indomitus as the hub-fortress Aquila Adamant, is one of the four Galilean satellites of the gas giant of Jupiter in the Sol System.

Once a Warp-tainted wasteland created by the malfunction of experiments designed to test the limits of Squat technology, Ganymede has been transformed on the orders of the primarch Roboute Guilliman into a massive hub-fortress of the Officio Logisticarum.

Its purpose is to supply, support, and archive the actions of the Indomitus Crusade's fleets and battle groups as they advanced across the galaxy.

Contagion of Ganymede
During the early years of the Imperium, Ganymede was a settled Imperial world. It was known to have had ancient Mechanicum habitats on its surface during the Great Crusade and Horus Heresy era and served as the central hub of the massive complex that made up the Jovian Shipyards.

At some time after the Heresy, the Adeptus Mechanicus began to perform experiments with Warp-coil technology that had been recovered by the Imperium from contact with the Squats. Unlawful experimentation with this technology led to the unexpected creation of a Warp Gate that unleashed the horrors of the Immaterium upon the Mechanicus facilities on the moon.

Imperial chronicles indicate that Ganymede was "lost" to the Imperium "forever" and had become "the eternal habitation of abomination."

The planet was declared a Quarantined World that was off-limits to any Imperial citizen on pain of death and orbital warning beacons were established which sought to prevent any void traffic from making a landing on the tainted moon.

Indomitus Crusade
Early in the Indomitus Crusade, the Primarch Roboute Guilliman issued the so-called "Borachae Decree" which declared that not only would the Officio Logisticarum be empowered to request military support and protection up to and including assigning tithed Astra Militarum regiments to their own protection, but they would also be furnished with planetary hub-fortresses from which to supply, support, and archive the actions of the Indomitus Crusade fleets.

The first hub-fortresses were established in the mustering systems where the initial Indomitus Crusade fleets gathered. In the Sol System, the Warp-tainted moon of Jupiter, Ganymede, was reclaimed during a highly classified purgation operation spearheaded by the secretive Grey Knights.

Even as the last banishment strikes were hitting home, enormous bore-engines went to work, expanding upon the ancient Adeptus Mechanicus laboratory complexes long abandoned beneath the surface of that troubled moon. Orbital defence platforms and void docks were manoeuvred into place even as indomitable fortifications rose upon Ganymede's surface and kilometres-long storage hangars were gouged through its bedrock.

Near the moon's core, priests of the Machine God installed immense Cogitators and data-archivium engines while the Adeptus Astra Telepathica sanctified twinned astropathic fortresses at its north and south poles.

Officio Logisticarum adepts in their thousands flooded into the moon's newly burrowed complexes of tunnels and chambers. Seconded Astra Militarum regiments -- some having just been pulled back from beleaguered war fronts elsewhere in the Imperium Sanctus -- invested its redoubts, bunkers, and defence turrets.

Warships cut menacingly through the void beyond its orbital envelope. Meanwhile, the first waves of supply ships and fuel tenders settled heavily into its void cradles, and astropathic communiques flooded into its newly opened ducts.

Ganymede had been wholly transformed, renamed as Hub-fortress Aquila Adamant.