Armored Core Wiki

A mobile fortress is a term for a large-scale weapon that are the precursors to Arms Forts in Armored Core 4. They are also called Behemoths.

10-4-2010 6-02-13 PM

The Fermi, an example of a Mobile Fortress.


A mobile fortress is a term for a large weapon that is similar to a massive MT form previous Armored Core games. Their sizes vary greatly, but generally are large, heavily armored units with powerful weaponry. Most weapons of this class are capable of easily decimating a NEXT. While they become mostly obsolete with the introduction of the larger and more powerful Arms Forts, they do appear on occasion.

A key feature of this particular group of weapons is that they are also usually equipped with Kojima technology such as Primal Armor and Kojima weapons on a scale surpassing a NEXT.

List of Mobile Fortresses[]

10-4-2010 6-02-37 PM

FF130 Fermi


Created by the nascent Interior Union, Fermi is an airborne fortress with the idea of mobility and defense in mind. To achieve this, Fermi has been equipped with thick armor and a powerful Primal Armor mechanism. For weaponry, this fortress equips a Melies Hi-Laser cannon which boasts impressive power and range capable of obliterating Primal Armor and massively damaging armor points, as well as extremely accurate missiles with long flight time and high maneuverability, making them extremely hard to avoid. It is first encountered in the mission Firefly.

In Armored Core: For Answer, a couple of Fermi are encountered in the Rescue GA Transport on Hard difficulty.


  • Hi-Laser Cannon
  • Verticle Missile Tubes
  • Primal Armor


25320 0 org

Ursragna as seen in the Gear Tunnel in the mission "Juggernaut."

The Ursragna is a gigantic weapon designed by one of the corporations and utilizes an advanced Primal Armor and multiple weapons. It is destroyed in the mission Juggernaut. This weapon was designed by Akvavit, who are well known for their Kojima technology. The fact that it was used against Anatolia shortly after GA's victory over BFF only reinforces this conclusion.

Several of these are seen in Armored Core: For Answer in the Eliminate Procyon hard mode. However, unlike in AC4, they are optional targets, and appear to be armed with either a large scale plasma cannon (similar to the Aretha's), larger laser cannons and a pair of rapid fire machine guns.


  • Pulse Cannons (?)
  • Laser Cannons
  • Machine/Chain Guns (ACFA only)
  • Large Scale Plasma Cannon
  • High Output Primal Armor

Sol Dios[]

For more on the Sol Dios technology, see Sol Dios.

Originally created by Akvavit, the Sol Dios cannon is a spherical Kojima weapon that is designed to fire Kojima charged bursts of energy. GA Europe would further enhance this weapon by developing an experimental mobile fortress unit to put this weapon on.


  • Sol Dios Kojima Cannon


  • Air Fortress Fermi has a striking resemblance to the Big Zam mobile armor from the Gundam Franchise, minus the legs and eyes.
  • Ursragna is a literal transliteration from Japanese ウルスラグナ (urusuraguna), which in turn is a Japanese transliteration of the ancient Avestan concept/deity of Verethragna, representing "victory".