Command Base (and its smaller counterpart, the Outpost) is a Posterity of The Sentinels building.
After the initial Evil Baby Corporation invasion of Polysiton, many of the Sentinels went hiding underground. However, many automated facilities still were operated and those in Arrybia were restored by Areus Megas and were used to combat the Infantid forces there in his adventures. The idea of a Mobile Command Vehicle was wrought from the Mobile Construction Yard of the old, which served as hubs that quickly established mechanical infrastructure and armament that Areus took advantage of. While the Mobile Construction Yard proved useful in the First Lampardian War, Sematia Aiakida made improvements to the old models in now the industrialized satellite of Euxeine. Whereas the Phrourion's models eventually grew less mobile as heavier facilities took root and expansionist modular system were placed, the improvements that Sematia made before Phrourion became an independent military arm were implemented to these bases: Sematia's emphasis on manufacturing and maintenance in the field were adopted, and these Command Bases not only build facilities, but they are also factories themselves, able to repair and manufacture vehicles interally.
Our allies, the Posterity of the Sentinels, operate their forces from these advanced facilities. Human ingenuity is a marvelous thing, for they have somehow managed to successfully miniaturize manufacturing of most vehicles and arms to be hosted by a very large yet mobile vehicle. These bases are unfurled from these vehicles, and these are the core of their army.
The Command Base is the heart of all our armies. Command Bases, and the vehicle form that is the Mobile Command Vehicle, are much more difficult to manufacture compared to the more simplified Pandora, so a commander can only have one. The Command Base will have more slots than a Pandora, and will perform more efficiently as well.
These bad guys have this cool bases which build their guns and cars. They also make ground from which other buildings sprout from the floor! These buildings also fix their cars as well. If we do get one, maybe we can have it build shiny awesome cars for us?
The Posterity emphasis on mobility is enshrined in their command structure. These Command Bases are the heart of their armies, and they constitute the focus of their operation. Command Bases can be furled back into the Mobile Command Vehicle and be moved as necessary, so deploy scouts if you suspect that they are shifting this crucial building elsewhere.
These collectivists are capable of innovation, which is surprising since self-interest is the ultimate source of innovation. While the base technology behind them is something that we have already achieved, the miniaturization and optimization behind them are far beyond our standards. They can be furled and moved, so strike when they're moving, but save the technology so that we may assume stewardship.