In NAD 172, the research team at the Tesla Reich Institute lead by Professor Bian Zoldark successfully developed a device capable of separately manipulating gravitational mass and inertial mass, and along with that a specialized high-efficiency reaction propulsion system through the acceleration of propellant utilizing this device. It was named "Tesla Drive" (テスラ・ドライブ), in reference of its birthplace. The Drive, however, wasn't capable of 100% separation between gravitational mass and inertial mass, and was thus incomplete. The controlled descent and subsequent investigation on Meteor-3 in NAD 179 by the EOTI Council resulted in the discovery of various pieces of Extra-Over Technology. One of them being a certain module which was capable of spatial manipulation through the deployment of a special "Dot Array" (ドットアレイ) force field filled with numerous mass action points. The EOTI Council researchers soon realized the benefits to the Tesla Drive that this new piece of technology could bring, namely how the Drive's gravitational-inertial mass separation could now be spread from a single point to throughout an entire field. With the implementation of the Dot Array system, the Tesla Drive was successfully miniaturized as a super high-efficiency reaction propulsion device. Furthermore, based on the Tesla Drive's operational data, some researchers theorized the possibility for a propellantless propulsion system, which was later implemented into the intersellar cruising plan Project TD.
Sensing the inability of the current TFF government to fend off an alien invasion as foreseen through analysis of Meteor-3, the EOTI Council secretly began development on Tesla Drive-equipped mass-production mobile weapons, one that could surpass even the TFF's own Personal Troopers. They were later known as Armored Modules. Genius robot engineering researcher Filio Presty was recruited to the development team, while Isurugi Heavy Industries offered sponsorship for the project.
Using Isurugi's YF-32 fighter jet's avionics as testing base, a semi-automomous control system integrating the Tesla Drive and related technology was developed, named as the "Learning-automation Integrated EO-technology and cONventional maNeuvering System", or "LIEOonN" => "LIEON" System for short. And thus, Bian designated the first four-limb test machine utilizing this system as the "Lion", signifying the birth of the Lion Series.
The Lion is a nimble and easy-to-produce mobile weapon, outmaneuvering the TFF's combat forces with its outstanding mobility through the installation of a Tesla Drive. Despite not faring well in close combat against Personal Troopers, the Lions nevertheless proved their prowess during the DC War as the DC's primary combat force. Development soon continued with the heavy artillery AM Barrelion, and then with the rather costly humanoid commander unit meant for anti-alien combat Guarlion. Following the end of the DC War, many of the DC's surviving Armored Modules still ended up being deployed by the TFF during the L5 Campaign against the Aerogaters, further serving as proof for their worth.
Aside from the Lion Series, other Armored Module lineages were also developed during the DC War, though despite being classified as AMs they were more similar in nature to one-off Special Units. These include the Valsion Series and the Granzon. Following the L5 Campaign, the aforementioned Project TD also yielded some results, in the form of the Series 77 of Armored Modules.
