Croi

Croi is a Feudal World, also classified by the Administratum as a Civilised World, located in the Aónor System in the Eastern Fringe of Ultima Segmentum, that serves as the Adeptus Astartes Homeworld of the Steel Hart Space Marine Chapter.

History
Croi is an extremely cold, forest covered planet where the temperature rarely rises above freezing. The harsh Ice World of Croi was originally a fertile World, though it's cold climate mede crops almost impossible to grow resulting in reliance on livestock. Many romanticised records survive of its colonisation by humanity, legends depicting a world ripe for conquest. Unfortunately, Croi was destined for catastrophe. Approximately twelve thousand standard years ago, just before the end of the Age of Strife, a damaged Ork warfleet descended on the world and proceeded to fight the Croi for every gram of the precious food they had stored. The Croi held out bravely for millennia in their vast hive cities beneath the canopies but were ultimately pushed back to the food vats. Eventually they destroyed the Orks by using ice boring machines to strategically strike at the heart of the mob, burning and melting most of the Orks and scattering the rest.

Even this Greenskin invasion proved unable to blunt the Croi's indomitable spirit. Their grim refusal to surrender, despite overwhelming opposition, had won them a historic, if bloody victory. After destroying the Ork invaders on their own world, Croi forces, in an act of vengeance, joined with the Steel Hart Chapter to cleanse their sector of the hated Greenskin menace.

After witnessing the danger an unguarded eastern front, the Steel Hart offered themselves to the Planetary Government, who gladly accepted. Even with their new protectors, the Croi continued to display the same stoic determination that they had shown in defence of the Hive Cities of their own homeworld. To this day, the courage and tenacity of the Croi in battle continue to earn them the respect and admiration of other Imperial Worlds from all over the galaxy.

Croi soldiers are expected to carry each and every item they will need to survive. Even with their thermal jumpsuits, they would not be expected to survive more than a week deep in the arctic forests of Croi while logging without them. The armoured battle tanks and artillery units of the planet are uniformly camouflaged in a manner suited to the frozen taiga of their world, and each vehicle proudly displays the name of their homeworld on its hull.

It is common for regiments of Croi to be assigned by the Imperial Guard to Arctic Worlds, due to their natural resilience to the cold. The Steel Hart are heavily involved with their people, the Planetary Governor consulting the Chapter Master on all matters of state, and Battle Brothers standing guard against the mega-fauna that prowl the planet.

Fortress-Monastery
The Heartforge is armoured and void-shielded to withstand any siege or bombardment that might befall it. Armed to repel attackers from land, air or space, its walls bristle with enough heavy ordnance to flatten a hive city. Every aerial approach to the fortress-monastery is overlooked by Icarus Pattern Lascannons, and a Macro-laser stands like a spear of vengeance to lance space-borne enemies from the heavens. The fortress-monastery's Librarius is a lightning-wracked spire where the Chapter's Librarians study their lore and chronicle the deeds of the Steel Hart. They also preside over the Chapter's Astropaths as they relay psychic messages throughout the void, communing with the greater Imperium and those Steel Hart across the galaxy.

The Heartforge is located in the Ais Croi mountain range, usually referred to as the Ais, the largest mountain range on the planet. The mighty Fortress Monastery is situated in the Valley of Fiáin alongside the Fionn's Fall. The Steel Hart's citadel is considered a wonder of engineering, containing graceful balconies, golden geodesic domes and slender glass walkways supported by silver-steel buttresses. The vast domed structures of the fortress are citadels in their own right. It contains such locations as Thetra, a rocky promontory overlooking a waterfall, accessible from the Fortress-Monastery. According to Croi legend, the Rock was where Cormac O'Airt, former High King of Croi, beheaded the rebellious Queen Sadhbh who had began a violent civil war lasting for several bloody decades. The Steel Hart themselves use the Rock as a place of execution, for members of the Chapter who have been condemned for serious crimes.

The Library of Oisín is the Librarium of the Steel Hart Chapter, located within the Heartforge, occupying an entire spur of the range of the Ais Mountains. It is named for its founder Oisín, the first Librarian born of Croi stock and considered to be the greatest poet and scholar ever seen by the planet, if not the Imperium. This Librarium is considered one of the greatest repositories of knowledge within the entirety of the Ultima Segmentum, and it has a reputation bested only by the Ultramarines' Library of Ptolemy. The Court of Attendance was one of the original landmarks that the Heartforge was built around, a wide courtyard set in the base of the Ais Mountains. The walls had advanced from the courtyard, leaving it some way from the edge where before it had stood at the brink of man-made cliffs.

The side nearest the Hive City of Tír, the capital of Croi, bears a monumental gateway, through which pilgrims from across the Sub-Sector come to offer praise for the Emperor and his Astartes. But the courtyard remains an important place where Croi's dignitaries and a contingent of an Astartes Honour Guard could greet an important guest with all the pomp and circumstance that they could muster.

The Spear Hall is a vast, expansive chamber that contains the precious Chapter relics that harken back to the earliest days of the Steel Hart. Suspended within a golden shaft of light, in the centre of the chamber, trapped in an anti-gravitic suspension field above the marble floor, is the legendary Fiacha, a spear crafted by the Master of Sanctity Fionn O'Cumhaill to combat the Splinter Fleet Fomoria.

The Laoch Crypts are where the dead heroes of the Chapter are interred by the Master of Sanctity. Located beneath the Spear Hall, it is the main site of pilgrimage for the worshippers who make the trek to the Heartforge, as one of it's deepest chambers hold those Astartes the Chapter believe to be free of sin, including Chapter Master Tarrasch Vast and Master of Sanctity Fionn O Chumhaill.