|Ultima Segmentum (Eastern Fringe)[1a]
Far to the galactic east of Terra lies the forge world of Triplex Phall. Located in the furthest reaches of Ultima Segmentum, in the Eastern Fringes, this forge world has grown autonomous through long periods of isolation. The Tech-Priests of Triplex Phall have discovered many pockets of worlds on the outskirts of the galaxy settled during the Dark Age of Technology. Many of these lost colonies were Knight worlds and some of them yielded technological secrets such as caches of STC designs, or unique archeotech.
While the star system was first established on Galatia during the early exploration of the galaxy[4c], by the time of the Horus Heresy Triplex Phall was part of a local empire alongside its two other sister planets, Galatia and Thule. Triplex Phall would prove to be the largest forgeworld of the triplets when the Emperor arrived, and provided its Titan Legion to the Great Crusade while Galatia and Thule's smaller Legions were left for local protection[4c]. All three were the site of heavy fighting in the Thramas Crusade during the Horus Heresy, where they resisted the Night Lords and fratricidal combat between the triple worlds' Mechanicum magi.[4a][4c] Triplex Phall's Tech-Priests initially turned to Horus' side at the beginning of the Heresy,[4c] but following the destruction of Galatia by the Dark Angels many of the traitors on Phall fled rather than face Lion El'Jonson's wrath. Loyalist Mechanicum elements launched an uprising and handed the planet over to the Dark Angels.[4b] Triplex Phall was the only world of the Triplex to survive the Heresy.[4c]
Triplex Phall designs appear throughout the weapons and equipment of the Imperial Guard, and their fabrication secrets have never been shared. Even delegations from Mars have been forced to return empty-handed, or with blueprints that they soon discover are missing vital details. Although Triplex Phall pays tribute to Mars like all other loyal forge worlds, this disobedience has prompted Mars to permanently deploy several Skitarii Legions to accompany Triplex Phall’s Explorator fleets and alert them should further caches of technology be discovered. The tactic has proved fortuitous, as Triplex Phall has suffered a series of invasions, and the extra troops greatly assisted in the forge world’s defence. First, a splinter of Hive Fleet Kraken was eradicated, followed by an attack by the Plague Fleet led by Typhus, and finally a Daemon incursion. All three attacks made planetfall, but were driven back before the foes could establish firm beachheads. This success was in part thanks to Triplex Phall being home to the Titan Legion Legio Victorum and having the support of over a dozen Knight Houses.
- 1: Imperial Armour Volume One - Imperial Guard and Imperial Navy
- 2: Imperial Armour Volume One - Second Edition: Imperial Guard, pg. 221
- 3: Codex: Adeptus Mechanicus (8th Edition), pg. 22
- 4: The Horus Heresy Book Nine - Crusade
- 5: Codex: Skitarii (7th Edition), pgs. 10-11 — Bastions of the Machine God