Castle Brian

This article is about Terran Hegemony defensive installations. For Clan equipment caches, see Brian Cache.

First constructed by the Terran Hegemony in 2391, each Castle Brian (plural "Castles Brian")[1] was a massive defensive fortress. They were built on numerous worlds during the Hegemony and Star League eras.

A sally port for one of the Castle Brian fortification complexes.


Named after Director-General Brian Cameron,[2] Castles Brian were originally constructed during the time of the Terran Hegemony as a buffer between it and the Draconis Combine, with the first Castle built on Telos IV. Within thirty years over a hundred more were built, all along the Hegemony's borders and on important internal worlds. While a tremendously expensive endeavor no one questioned the Director-General's decision to build them, and events during the Age of War would prove this effort to be prudent.[3][4] In the wake of the Reunification War, with the formation of the Star League, the Star League Defense Force took control over these structures and more were built in the Periphery as a means of controlling the rebellious population.[5][4] Unfortunately when First Lord Richard Cameron withdrew the SLDF from the Rim Worlds Republic in 2755, he gave control over these Outpost Castles to his good friend Stefan Amaris. Amaris' troops occupied these fortifications and studied them so that, with the onset of the Amaris Civil War, Republican forces had a thorough understanding of the structures and how to defeat them.[6][4] The total number of Castles Brian constructed has never been found, in part thanks to the skill of the Hegemony in building them right under the noses of friends and allies, and as a result many became lost after the end of the war as Aleksandr Kerensky took the surviving SLDF with him on his Exodus. Soon even the method of their construction became lostech, as did many other wondrous technologies like stasis chambers and weather control satellites. The over twenty Castles located on Terra were eventually taken over and used extensively by ComStar, which were in turn taken over by the Word of Blake.[4]

Castle Brian Devils Tower.


The textbook definition of a Castle Brian had a minimum of twenty heavily armed turrets carrying an assortment of direct fire and missile weaponry, fifty smaller turrets and a hundred smaller antipersonnel bunkers. These were usually the only visible structures of the fortress, which was usually built deep inside a mountain and safe from all but the heaviest nuclear or orbital bombardment. An average of ten levels allowed enough space to store two brigades, which could quickly emerge from any of five secret exits.[7] The reality was that no two Castles Brian were alike, and there were several different classifications for these types of fortified structures. Almost as impressive as the structures themselves were the lengths taken to build them in secret in some of the remotest regions of a planet, including diverting an entire sea to build a Castle on the seabed and flooding the area once more.[4]

While often mistakenly believed to have been built to prevent invasion or takeover of a planet, the static fortresses were not meant to protect anything other than themselves and the forces contained within. With the limited resources of the Terran Hegemony compared to the nations of the other Great Houses, and the later Star League's sheer size preventing blanket defense coverage of most worlds, a Castle Brian was intended to be a hindrance against a blitzkrieg invasion, storing enough weapons, food and men to allow any defenders to hold out and harass the invaders hopefully until reinforcements could arrive. In effect their very presence acted as a deterrent against invasion for, while an enemy may succeed in capturing a planet, the presence of one or more Castles would prevent them effectively controlling it bar sufficient garrison forces.[7][4]

Known Castles Brian[edit]

The exact number of Castles Brian in the Inner Sphere and Periphery is unknown, but in 2423 the League had already 120 of them. The planet with the largest number (outside Terra) was Lambrecht, with six of them.[8]

Earth had at least twenty. On the planets in a radius of thirty light years around Earth, there are eighty-three.[9]

See also: List of Known Castles Brian.

Castle Brian Classifications[edit]

The SLDF divided the defense structure into several classes as described below.

  • Castles
    The precursor to the modern Castle Brian, Castles were built on important or rebellious worlds, often into the sides of a mountain or beneath meters of concrete. Castles were stockpiled with weapons and honeycombed with tunnels to allow the garrison to set ambushes.[4][10]
  • Castles Brian
    The most famous and awesome example of a castle were the Castles Brian, the first ones creating a chain of fortresses around the Hegemony and making its hostile neighbors think twice before invading. Full-sized Castles Brian could hold up to two brigades and extended for hundreds of kilometers underground, essentially forming its own city.[4][10]
  • Outpost Castles
    After the Reunification War the SLDF built many Outpost Castles, essentially Castles Brian on a smaller scale, on rebellious worlds in the Periphery. The Rim Worlds Republic's occupation of their Outpost Castles allowed for a thorough understanding of these fortifications and led to the deaths of many SLDF troopers during the Amaris Civil War.[4][10]
  • Port Castles
    These complex variations on the traditional Castle Brian had a small spaceport built into a highly-protected position, allowing the forces within to more easily be relieved during battle. No matter how well-defended these spaceports where they still represented a serious vulnerability in the fortress' defenses; consequently few Port Castles were built.[4][10]
  • Mini-Castles
    Mini-Castles were Castles Brian on a much smaller scale, with fewer entrances and the capacity to hold only one regiment. Often a Castle Brian would have a ring of Mini-Castles built around it to serve as a first line of defense.[4][10]

Castle Brian Structures[edit]

Brian Caches[edit]

The term Brian Cache, describing a Clan equipment store (typically one established during the demobilization process Kerensky created upon arriving in the Pentagon Worlds), is derived from the Castle Brian fortresses.


  1. Archive of official CBT forum reply by Herbert A. Beas II
  2. Archive of official CBT forum reply
  3. The Star League, pp. 25–26
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 Jihad Hot Spots: Terra, p. 201
  5. The Star League, p. 64
  6. The Star League, p. 80
  7. 7.0 7.1 The Star League, p. 29: "Castle Brian Fortresses"
  8. Star League, p. 29
  9. Historical: Liberation of terra II, p. 28
  10. 10.0 10.1 10.2 10.3 10.4 The Star League, p. 132