Battle of Mt. Fuji

Background
After Lelouch's actions at the Tokyo Settlement, which resulted in Lelouch taking all the UFN representatives hostage, the Aerial Fortress Damocles is first unveiled, obliterating Britannia's capital city, Pendragon, with a F.L.E.I.J.A. strike.

To Lelouch and Suzaku's surprise, Schneizel reveals that Nunnally is alive and well. However, she declares herself to be Lelouch and Suzaku's enemy, leaving Lelouch despaired. Nevertheless, the Damocles advanced through Japan on its plotted course to the Yellow Sea, from where it would ascend into orbit and into a position to target the whole world at once. However, Lelouch decided to take the fight to Schneizel, bringing the full might of the Britannian Military onto the Damocles with its escorts, including The Black Knights, as it was passing over Mt. Fuji, Japan, Before the battle lelouch gives his speech to his entire Royal Guards and his other Forces.

The Battle
The battle begins with Schneizel extending the UFN forces outwards to prevent Lelouch from outflanking him. Lelouch attempts to make dozens of false openings, but Schneizel saw through various attempts to get him to attack. Both the UFN forces and the Britannian military have locked in a stalemate until Schneizel found an opening that allows the Black Knights to make a opening right through the center line where the Avalon is positioned, forcing Lelouch to keep drawing back. The skillsets and the mind of the Black Knights were able to pierce right through the frontlines to get to the Avalon, but it leaves them exposed to Lelouch's backup plan As the creation of the F.L.E.I.J.A. Eliminator was underway, Lelouch remotely detonated the Mt. Fuji' Sakuradite mines, resulting in a volcanic eruption that decimated much of the Black Knights forces and sacrificing his own forces as well, including Ikaruga, which downed near the mountain and was subsequently evacuated. With Schneizel's forces cut in half, the commander was forces to deploy the multiple F.L.E.I.J.A. warheads onto the Britannian ranks, battle turning into wholesale slaughter. After seeing that F.L.E.I.J.A.'s detonation could not be prevented by destroying the warhead, Lelouch orders all Units to spread their ranks and fall back, and that went for Avalon, too, - even with its Blaze Luminous shielding, it was too dangerous to expose his flagship. Schneizel also decided not to target Avalon, as there were hostages on board.

Once the F.L.E.I.J.A eliminator was complete, Lelouch changes tactics to charge right into the Damocles with the entire hostages onboard. The remnants of the Black Knights who managed to survive the eruption regroups to make a counterattack against the Avalon. Suzaku, in his Lancelot Albion, manages to defeat some of the Black Knights, including Kyoshiro Tohdoh and Shinichirō Tamaki. However, Avalon is also damaged and forced to land, with Lelouch leaving the ship aboard his Shinkirō, already fitted with a F.L.E.I.J.A. Eliminator. As he does, however, the Black Knights' boarding party, led by Li Xingke aboard his Shenhu, boards the Avalon, proceeding to rescue the hostages. After the F.L.E.I.J.A. is disabled mid-flight, Lelouch creates an opening in Damocles's Blaze Luminous, allowing Lelouch and Suzaku to board the station, Gino trailing after them and destroying the Shinkirō, before being defeated by Suzaku. Suzaku, however, challenges Kallen on her Guren S.E.I.T.E.N. in a duel outside the Damocles. As a result, Lancelot Albion was utterly Destroyed, and the Guren was severely Damaged. Meanwhile, Jeremiah Gottwald defeats Anya Alstreim aboard her Mordred, but uses his Geass Canceler on her instead of killing her.

When aboard, Lelouch proceeds to take the majority of the Damocles' personnel under his Geass. Afterwards, he fools Schneizel into believing that he was on the command deck, surprising Schneizel when he arrives into his almost-launched shuttle instead. Lelouch uses his Geass on Schneizel, making him serve Zero.

One obstacle is then left in Lelouch's path - Nunnally, who holds the key to the Damocles, and has been launching the F.L.E.I.J.A.s. She regains her sight, breaking Charles's Geass, and asks Lelouch if he would use his Geass on her to obtain the key. After being told that Damocles is made to focus the world hatred, he proceeds to do so, taking the key from her and gaining absolute control over Damocles' destructive power.

Outcome
With the Damocles in his hands, Lelouch declares himself the ruler of the world. In the remaining two months, the remnant Black Knights are rounded up, and repressions and pacifications of the conquered world begin. After the time skip, the Zero Requiem concludes with Lelouch's death at the hands of Suzaku (as Zero). The Damocles was destoyed by sending it flying into the sun.