The Sky Fortress Damocles (天空要塞ダモクレス Tenkū Yōsai Damokuresu) is a floating fortress developed by the Toromo Agency at Cambodia. It serves as the main base for Schneizel's splinter faction. Based on its schematics, it is powered by a series of solar cell generation systems, similar to those used in Tokyo's concession areas. Spanning three kilometres on its longest axis, it is armed with several F.L.E.I.J.A. warheads, however it requires approximately ten minutes to reload after firing just one. It is also rendered nigh indestructible due to the Blaze Luminous shield that encompasses the entire fortress. Its only weakness lies in the fact that the Blaze Luminous has to be opened near the F.L.E.I.J.A launch tube in order to fire a F.L.E.I.J.A.
The Damocles was originally developed by the Toromo Agency in Cambodia at the request of Schneizel el Britannia. The fortress remained under construction for much of the second season, completed after Lelouch vi Britannia ascends to the throne of Britannia in 2018.Damocles was first deployed to the Holy Britannian Empire , where it obliterated the imperial capital city, Pendragon, with a F.L.E.I.J.A. warhead that had its limiter removed, displaying the weapon's increased destructive yield. The Damocles then steadily gained altitude in the days after the attack, and entered the airspace of Japan during the Battle of Mt. Fuji, where it used several F.L.E.I.J.A. warheads against Britannian air forces. The Damocles continued ascending, moving over the Pacific Ocean on its predicted course. Unassailable due to its powerful Blaze Luminous, the Damocles remained unscathed during the battle.
After the completion of the F.L.E.I.J.A Eliminator during the battle, Lelouch vi Britannia, Suzaku Kururugi and several Britannian Knightmares used the weapon to cancel the detonation of one of the warheads before using a small window in the Damocles' shields to infiltrate the fortress. Inside the Blaze Luminous , Suzaku Kururugi duelled Gino Weinbergand Kallen Kōzuki using the Lancelot Albion, but Suzaku was finally defeated. Inside the fortress, Lelouch cornered Schniezel and defeated him by casting his Geass. He then confronted Nunnally vi Britannia and obtained the Damocles' main firing switch from her, ending the battle with victory for him and the Britannian Forces. He then declares himself the absolute and unopposed ruler of the world.
Emperor Lelouch, after the Battle of Mt. Fuji, placed Marrybell mel Britannia in charge of the fortress in his stead, and it is assumed that he used the Damocles to destroy and threaten any Country which tried to oppose him. Prior to the plan to assassinate him, Nonette and the Glinda Knights, and Peace Mark, planned an attack on the base.
After the assassination of Lelouch vi Britannia, the Damocles was destroyed by sending it to the Sun.
- Damocles is a fictional person from Greek mythology, a courtier of King Dionysius who was given the chance to see what it was like to be king for a day. But the king arranged to have a sword hanging above the throne by merely a horse hair, until Damocles begged to be allowed to step down. Cicero (the author) used the story to ask the audience, "Does not Dionysius seem to have made it sufficiently clear that there can be nothing happy for the person over whom some fear always looms?"
- Thus the name of the fortress itself, which was supposed to usher an era of world peace and happiness, is an ironic play on what Lelouch and others argued all along, that true peace and happiness cannot be brought about through tyrannical rule and the constant threat of space-borne weapons of mass destruction.
- The idea of Damocles to preserve world peace is similar to the Death Note used by Light Yagami from the series Death Note where both weapons (Death Note and Damocles) would rule the world under fear but the main difference is that Damocles would cause more destruction whereas the Death Note would limit the world to good and obedient people.
- Nagato from Naruto had a plan similar to Schneizel's use of Damocles where he would use the tailed beasts to create a deadly weapon so powerful that could wipe out one of the five great nations in an instant to create a cycle where people would live peace under fear of being wiped out by the weapon and if they do not, they would use it again.