Libra was a giant space battleship commissioned and built by OZ and designed by the five scientists who created the Gundams. In form, Libra resembles five geometric diamonds, four of which are connected to a corner of the fifth in the center. Its name is derived from the Zodiac constellation Libra.
As a battleship Libra was well suited for its role possessing numerous defensive guns and capable of carrying hundreds of mobile suits. However its most powerful weapon is a massive beam cannon located in the central diamond. The devastating power of this cannon was unparalleled, however it was fired very rarely as the scientists who designed it made sure the weapon would be flawed and would break down after each time it was fired and required days to repair.
One of Libra's more unique features was a control room Zechs Merquise had built that incorporated Gundam Epyon's combat computer/pilot interface system. The purpose of this room was to allow an individual to command White Fang's mobile dolls in combat aided by the combat computer. This room was used exclusively by Dorothy Catalonia.
The Romefeller Foundation ordered the construction of Libra after gaining the trust of the colonies. The main reason for building the monstrosity was because they needed a new example of power, as they had to place the OZ leader and figurehead Treize Khushrenada under house arrest. However, White Fang managed to capture it thanks to their new mobile doll army and complete its construction.
Upon completion, White Fang leader Millardo Peacecraft made his declaration of war against the entire Earth by firing Libra's main cannon on an island.
The Eve War
Eventually the leadership of White Fang decided to use the battleship to recreate the original Operation Meteor by dropping it onto Earth, after the battle stations main cannon is destroyed by Peacemillion's ramming into it. The explosion created by Libra and Peacemillion crashing to Earth would create an endless winter and life on the planet would end.
As Libra made its war towards Earth it was encountered by the Gundams and an Earth fleet composed of Space Leos lead by Treize Khushrenada in the OZ-00MS2 Tallgeese II. Despite having Peacemillion crashed into its main cannon, Libra's main engines were working to around 70% capacity and were able to send the battle ship on its collision course with Earth.
Whilst Duo was looking for Heero on board the damaged space fortress, the God of Death finds the five Gundam doctors in a cell. Doctor J explains that if they get onboard Peacemillion and activate its boosters, it will throw Libra of course and cause it to explode harmlessly in space. When the doctors reach the controls for Peacemillion, they are confronted by Quinze but that doesn't stop Doctor G from activating the Peacemillion's engines. The engine room then explodes, killing the six men, as the engines reach full power. The Libra is stopped in its tracks, however one of Libra's sections separated and continued forward towards Earth. It is stated even if this one section of Libra hits Earth, it will still cause an endless winter.
As it continues to fall, the final battle between Heero Yuy/Wing Zero and Millardo Peacecraft/Epyon comes to an end within the falling block. Heero defeats Milliardo but spares his life and goes to the powerplant within the block. Heero lost his Twin Buster Rifle during the battle with Millardo so decides the only way to destroy the section is self-detonation. Moments before Heero activates the self-detonation on Wing Zero, Millardo arrives in the damaged Epyon and announces his return from the 'dark side' and says Heero must survive. Milliardo then uses Epyon's beam sword to destroy the powerplant (Epyon and Milliardo are presumed to be destroyed).
The falling section of Libra blows up but part of it remains intact and continues to fall towards Earth. Although not large enough to wipe out all of humanity, it could still cause a massive amount of damage. Trowa, Duo and Quatre then attempt to break down the remaining block until they hear that Wufei has returned Wing Zero's Twin Buster Rifle. The four pilots escape the Libra block and Heero races into the atmosphere to get ahead of the block. Although it looks bad for Heero and the Earth, Lady Une is sure that after what she has seen, the Gundams can accomplish anything. Evidently, Heero blasts the remaining block with his Twin Buster Rifle, destroying the pieces structural integrity forcing it to break apart from the friction from the atmospheric reentry. The debris scattered and burned up harmlessly in the atmosphere visible as a meteor shower from the Earth's surface.
The rest of Libra and Peacemillion is last seen floating away from Earth and it is unknown whether either battleship exploded taking the other with it or if it just drifted into space.
In the original manga adaptation of Gundam Wing, Libra sets itself on its own falling course to Earth and, as Heero and Zechs' duel is on the outside of the spacestation, Zechs is unable to attempt to sacrifice himself. Doktor J ends up detonating Peacemillion to stop Libra, but the entirety of the spacestation is obliterated when the Wing Zero, Epyon, Sandrock, Heavyarms, Altron and Deathscythe Hell channel their power into the Twin Buster Rifle, taking it out in one shot.