Second Assault on Tokyo Settlement

Background
By forming the United Federation of Nations, the world are basically split between UFN and Britannia. Immediately, numerous war fronts sprung up, with equal gain and losses on bother side. In order to break the stalemate (and for UFN, liberate Japan), the leaders of UFN and Britannia had determined that they need to secure the Area 11, particularly the Tokyo Settlement.

The Battle
Lelouch was successful and distracted the Britannian military, and activated the Gefun Disturbers he had previously hidden on the monorail system of the Tokyo Settlements. Thus, Britannian 5th Generation Knightmare Frames and older do not work due to Gefjun Disturbers. He then ordered the Ikaruga to launch with a fleet from the sea to assist him in the battle. Meanwhile, Schneizel El Britannia has placed a fleet infront of Mt.Fuji, all of which contain 6th and above Generation Knightmare Frames. He orders them to intercept. After a few hours of battles, Britannia successfully took out the Gefun Disturbers, and begin to turn the tide against UFN.

During this time, Zero had sent in a special force into the Area 11 Government building to secure Nunnally vi Britannia and rescue the Commander of Zero Squad, Kallen Kozuki. After being rescued, Kallen, using the new Guren SEITEN, decimates the Britannian forces. Luciano and the Valkyrie squadron are also killed by her, as are an untold number of support units. She then fights Suzaku Kururugi, easily breaking through his defenses and bringing him to the brink of death.

Eventually, Suzaku Kururugi, under the influence of his "live" Geass, fired the nuclear FLEJIA warhead at Guren SEITEN. It missed, and exploded above Tokyo Settlement, engulfing the settlement in a giant ball of light.

Aftermath
A majority of Tokyo Settlment, along with 10 million population, perished under FLEJIA attack. During such chaos, Britannia had sent an envoy, and exposed Zero as Lelouch Vi Britannia. Thus, the Black Knights negotiated a truce with Britannia without approval from UFN, and attempted to execute Lelouch. However, his escape forced the Black Knights to release information to the public that Zero was killed during the Second Battle of Tokyo Settlement.