|This article is about the space vessel, for the novel by Ben Counter see Phalanx (Novel)|
Phalanx is the mobile fortress-monastery of the Imperial Fists. Officially, the homeworld of the Imperial Fists is Terra, but in functional terms the Chapter has been fleet based and used Phalanx as its primary base of operations throughout its entire history.
The origins of Phalanx are contested in the background material, of which there are two accounts:
- The Index Astartes entry for the Imperial Fists holds that the origins of the starship are unknown, but is believed to have been constructed during the Dark Age of Technology, predating the Imperium. In this account, the vessel was discovered by Rogal Dorn prior to being reunited with the Emperor of Mankind. Upon encountering his father for the first time, Dorn was manning the helm of Phalanx, which he offered to the Emperor as a gift. The Emperor declined and willed that Dorn use the ship in carrying out his command of the VII Legion.
- The Lightning Tower by Dan Abnett gives a more recent but far less extensive account, stating that Phalanx was built by Rogal Dorn himself and evidences his excellence in constructing fortresses.
The capabilities of Phalanx are substantial. Entire portions of the vessel are used to emulate different combat environments for training purposes. Her foredeck is so large that it can dock a dozen large cruisers and has developed its own ecosystem, complete with unique species of animal life that have had their own evolutionary history aboard the ship.[3a]
The interior of Phalanx incorporates stone corridors, archways, and cathedral elements. As of the very beginning of the Horus Heresy, the starship featured a gallery that displayed the battle honors of the Imperial Fists, which stretched for kilometers.[3a] Of course, the ship continues to house Chapter honors and relics. Among the most prized are the Remains of Rogal Dorn and the battle honor Roma.
However, sources differ on the general shape and exterior character of the ship. The different descriptions include:
- A structure of "towering forests of spires interlaced with flying buttresses"
- A structure that leads observers to believe Phalanx "might have been a planetoid or minor moon," perhaps implying a spherical shape.[3b]
- A ship that is "many kilometers long, triangular in cross-section with its upper surface bristling with weapons and sensorium domes. Two wings swept back from the hull, trailing directional vanes like long gilded feathers. Every surface was clad in solid armour plating and every angle was covered by more torpedo tubes and lance batteries than any Imperial battleship could muster" and with "thousands of battle-honours and campaign markings all over the beak-like prow."
As of 999.M41, the 3rd Company is defending Phalanx from a Daemonic boarding action led by Iron Warriors Warsmith Shon'tu and the Daemon Be'lakor. Shon'tu and Be'lakor are seeking to outdo Abaddon's 13th Black Crusade by infesting the massive starship while on station in the Sol System and using it to bombard the Imperial Palace. Captain Tor Garadon is commanding 3rd Company's defense of Phalanx. His forces have inflicted extreme casualties on the attackers and maneuvered Phalanx into the warp in order to protect Holy Terra should they fail in repelling the assault. The Legion of the Damned have arrived to assist Garadon's forces as the battle grows desperate. The batting is continuing at present with no certain outcome. 
- 1: Index Astartes II: Imperial Fists, p. 12
- 2: The Flight of the Eisenstein (Novel) by James Swallow: Chapter Fourteen
- 3: Sons of Dorn (Novel) by Chris Roberson
- 4: Phalanx (Novel) by Ben Counter, Chapter One
- 5: The Lightning Tower (Short Story) by Dan Abnett, pg. 6
- 6: Black Library.com
- 7: Codex: Sentinels of Terra, The 3rd Company's Triumph