Aetna

Aetna, known also as Trinakyron II by the local inhabitants, is an ocean world that serves as the Adeptus Astartes homeworld of the Forge Templars Space Marine Chapter. Following their inception in the mid-500's.M32, during the 4th Founding, the newly created Forge Templars chapter was granted sovereignty over the Trinakryon System, in Segmentum Ultima. The chapter's fortress-monastery was established on the biggest island of the ocean world, Aetna, dominated by the mighty volcano Eolos. In the mountain's bowels the chapter established a great forge where the material from their interplanetary fiefdom are transformed in armours and weapons for the Forge Templars.

Background
The Forge Templars homeworld is the Ocean World of Trinakryon II, commonly known as Aetna. Aetna's surface is dotted by numerous small island, the biggest of them being Eolos, site of the Forge Templars' Fortress-Monastery. Aetna's fauna is characterized by a stunning variety of reptilian creatures. From the diminutive scalewings, to the deadly tarrasques, almost every evolutionary niche of the planet is occupied by reptiles.

The planet's population is relatively scarce, given the reserved nature of the chapter. Aetna, however boasts an impressive array of orbital facilities; not only the mighty defences sported usually by Astartes homeworlds, but also a very active orbital harbour thanks to the continuous flow of raw materials from the rest of the system.

Trinakryon System
The Trinakryon system is located in Ultima Segmentum, near its coreward border. According to many xenogeologists the conflicting gravity pulls from the vicinity to the galactic core supermassive black hole and the gravitational pull of Trinakryon itself (a white dwarf star) created an area where a considerable amount of metals and rare elements accumulated, making the system incredibly rich in precious ores.

Its most noteworthy planets are:
 * Aetna (Ocean World): The poorest planet in raw materials but arguably the most important as homeworld of the Forge Templars astartes chapter and processing centre for the ores mined in the rest of the system (for details see above).


 * Hymera (Desert World): Hymera is one of the driest planet of the sector; with an almost unsustainable thermal excursion. Despite the harsh conditions Hymera is one the most densely populated planet of the system. The human settlements are located deep under the surface, built in natural caves as well as in abandoned mining tunnels. Photovoltaic power plants dot the surface of the planet providing energy to the miners. Its most important production consists in adamantium and other metals.


 * Kamarya (Death World): Kamarya is the nearest planet to the sun, and the smallest, Kamarya suffers from great geological instability due to its strong volcanic activity and the fact that its moon, Akargas, has a mass comparable to 3/4 of the planet. These features make Kamarya's surface a hellish landscape dotted by fiery chasms and fumaroles. Earthquakes are also very frequent. Yet, the very characteristics which make the planet a Death World, give it a stunning wealth in precious ores and promethium. Too great a bounty to overlook, humanity has slowly settled and thrived. Great Hive cities rise from the sulphur mists like mangrovies, while spider-like colossal harvesters roam the surface.


 * Hyaela (Penal World): Hyaela is a barren world, chosen from the Adeptus Arbites and the  Officio Praefectus as a penal mining colony before the Forge Templars chapter established on Aetna. As such the planet is the only one which does not devolve all of his production to the chapter, though it still pays a tithe. As in many penal colonies, inmate revolts are very common and usually dealt swiftly by the brutal garrison. The most noteworthy uprising happened in 209.M41 leading to the brutal and swift purge known as “The Punishment of Hyaela” (see above).

Fortress-Monastery
The Forge Templars Fortress-Monastery is known simply as ' The Forge ' by the chapter itself, while in official Imperial records it is named ' Mount Eolos ' after the eponymous volcano where the fortress lies. The chapter took advantage of the insular position of the volcano and fortified it focusing especially on anti-aircraft installations and orbital bombardment countermeasures as the raging seas of Aetna offer a natural protection against infantry and armour based assault.

The fortress itself consists in a series of concentric rings, with the volcanic chimney at the centre. Nearest to the chimney is the immense chapter forge. It is in fact a complex of chambers built along the volcanic chimney from the roots to the mouth of Mount Eolos. The lower is the chamber, the more important is the Techmarine in charge because it is nearer to the planet's mantle and the magma is hotter. In the deepest forge chamber the honoured Dreadnoughts of the chapter lie in stasis. The middle rings house the chapter hall, the sparring cages and the Reclusium. Near the top of the mountain is sited the Librarium. The external rings are the battlements with their impressive gun emplacements. At this level there are also many fortified landing pads to connect the Fortress-Monastery to the orbital docks.