Castrum Pocket WarShip
Production information
Manufacturer Boeing Interstellar
Production Year 3097
Use Missions
  • Frontline Combatant
  • Command Vessel
  • Fire Support
  • Fighter Carrier
Type Military Spheroid
Tech Base Inner Sphere (Experimental)
Technical specifications
Mass 100,000 tons
Structural Integrity 150
Length 114 meters
Width 124 meters
Height 324 meters
Drive System Fusion
Safe Thrust 3
Max Thrust 5
Fuel (tons) 1,000
Fuel (days) 1.84
Armament Main Weaponry
Armor 540 tons heavy ferro-aluminum
Fore: 1,305
Sides: 1,153
Aft: 1,003
Crew 110 + 162 bay personnel
  • 20 officers
  • 20 enlisted
  • 70 gunners
Escape Pods/Life Boats 0/50
Small Craft/
AeroSpace Fighters
Heat Sinks 600 (1,200)
BV (2.0) 67,223[1][2]


Produced by the Republic of the Sphere, the Castrum-Class Pocket WarShip was the answer to the nation's need to improve the firepower for their then fledging Border Fleets. The largest combat Dropship ever produced, the Castrum was the brain child of Vice Admiral Christoff Brennan Wright, who backed efforts to develop the ship to fill out the Republic's fleets. Part of the reason was due to many of the Word of Blake designs that the Republic inherited and put into production were reassigned to ground based military formations at the time.[3]


The first notable usage of the Castrum was at the end of the Second Combine-Dominion War in 3101, where the Republic was called in as special investigators by Clan Nova Cat. Among assets dispatched by the Republic were some Castrums, which served as part of a special fleet that was assembled to traveled to the Irece Prefecture to protect the investigators and the Nova Cats. These ships would remain in orbit over Labrea and Irece maintaining the peace between Ghost Bear invaders and Draconis Combine and their Nova Cat peoples. The presence of the Castrum help maintain the reassuring presence while investigators could looked into actions of the war. The ships would remain on station until 3103, where they would return to the Republic and rejoin the Republic's WarShip Command.

During the Capellan Crusades, Castrums assigned to the Fifth and Sixth Border Fleets were used to as deterrents against House Liao black naval forces. However, those fleets commands were cautious in using them. Their presence in large naval formation which helped to keep naval engagements from escalating into large conflict between nations.[4]

Weapons and Equipment[edit]

Launched from Boeing Interstellar's facilities at New Earth, the Castrum's unusual size offered challenges in their deployment. The ship is strictly a spaceborne vessel and to transport them requires two of the Docking Collars on a JumpShip.

The ship was intended to be the center of a naval task force, and for this mission they were fitted out with Naval C3 systems. The computers would tie into other Republic vessels using Naval C3 such as newer variants of the Achilles, Tiamat, and Dragau II classes of DropShips and helped to better coordinate their collective firepower.

The Castrum's weaponry is arranged similarly to that aboard WarShips, with their Sub-Capital Cannons which can be used for orbital bombardment or in bracket fire to shoot down incoming smaller spacecraft. Castrums are generally armed for long range engagements, using Capital/Subcapital guns along with some of its conventional weaponry. The ships are noted for their better than average targeting abilities at long ranges.

The ship's main capital-grade firepower comes from its sixteen AR-10 multiple missile launchers, which are mounted in its front arcs in sets of eight. These launchers have full complements of Killer Whales, White Sharks and Barracuda missiles.

Its complement of Medium and Light Sub-Capital Cannons are arranged with the Lights being focused on the bow and aft-sides, while the heavier Medium Cannons are mounted in the forward sides with the AR-10 launchers. Anti-Missile Systems are fitted in clusters of 5 systems, in each front side facing, and to the aft. For more conventional weaponry the Castrum relies on its heavy battery of Improved Heavy Gauss Rifles, which are mounted on all sides and in the aft to aid in protecting the ship from smaller threats as well as assisting in the taking down of larger threats.

For its defenses, the Castrum has large quantity of Heavy Ferro-Aluminum Armor, with over 540 tons giving the ship ample protection in a prolonged fight. Though not necessarily equipped to carry fighters, the ship's small craft bay is capable of carrying light fighters in place of small craft. Initially the Small Craft assigned to the ship can be used to transport the ship's compliment of Battle Armor squads to board other ships, should need arise.[5]


As a dedicated transport the Castrum has three cargo bays:[6]

Design Quirks[edit]

The Castrum has the following Design Quirks;


As of this writing, there is no MUL Profile for the Castrum and the record sheet is only published in XTRO: Republic I.

The Naval C3 System is the only device that remains listed Experimental Technology as of 3145. Other weapon/equipment listed in the Castrum as experimental was the Improved Heavy Gauss Rifles which was re-rated as Tournament Legal/Standard Technology as of 3081.[7]


  1. Experimental Technical Readout: Republic, Volume 1, pp. 15, 34 Castrum Pocket WarShip - "Battle Value 2 on both Record Sheet & Article listing."
  2. Technical Readout: 3150, p. 220
  3. Experimental Technical Readout: Republic, Volume 1, pp. 15, Castrum Pocket WarShip - "Background of the Ship"
  4. Experimental Technical Readout: Republic, Volume 1, pp. 15, 34 Castrum Pocket WarShip - "Background of the Ship"
  5. Experimental Technical Readout: Republic, Volume 1, pp. 15, 34 Castrum Pocket WarShip - "Stats and other mechanical features."
  6. Experimental Technical Readout: Republic, Volume 1, pp. 15, 34 Castrum Pocket WarShip - "Cargo Bays and type."
  7. Technical Readout: Prototoypes, p. 206 Jihad Technology Advancement Table - "Improved Heavy Gauss Rifle re-rated from Experimental to Tournament Legal. Naval C3 not listed, thus not changed from Experimental.