Deimos, also known as the Iron Fortress of Mars, is one of the moons of Mars. It is primarily used as a military fortification and museum.
Deimos was colonized after Phobos and Mars were. With the construction of the Martis Shipyard Construction Network on Phobos, Deimos was selected to become a military base, designed to protect Mars and Phobos from incoming attacks, or large asteroids that may collide with Humanity's second home. Over the centuries, it has been constructed into an enormous military fortification. The fortresses and defenses began to tower from the surface of Deimos. Over the centuries, it eventually earned the nickname: "The Iron Fortress of Mars."
While still completely able to act as a military installation if the need arises, the moon is now more often considered a museum, and is open to the public for visits to see the great defensive installation. It also serves as a training ground for military forces of the Federations of United Star Systems.