Battle of Babel Tower

Battle of Babel Tower was an event that occurred in Code Geass: Lelouch of the Rebellion R2.

Summary
The Black Knight Hotel Incident began with the remnants of the Black Knights led by C.C. searching for Lelouch Vi Britannia in the Babel Tower. Kallen, who was already inside the casino disguised as a waitress, eventually came across Lelouch, who was with his brother Rolo. Her attempt to sway him to her side was foiled, however, when a man known as 'King' interrupted. After banter, Lelouch challenged him to a chess match. Although Lelouch emerged victorious, King claimed that Lelouch had cheated to win, and ordered his bodyguards to eliminate Lelouch. At this moment, the Black Knights broke into Babel Tower by entering through the roof via an airdrop, using a commercial airship commandeered by C.C. Simultaneously, Kallen knocked out both King and his bodyguards, and fled with Lelouch, and the battle begun in earnest.

The Battle
Calares, the new Governor of Area 11 after the disappearance of Cornelia Li Britannia after the Black Rebellion, caught sight of the assault on the tower from the middle of the Tokyo Settlement as he was conversing with Li Xingke and Gao Hai, who had recently arrived in Area 11 from the Chinese Federation. Meanwhile, the Black Knights were taking control of the facility relatively unopposeed, save for a small unit of Sutherlands headed by an un-named Britannian commander, whose unit was under direct orders from the Emperor to crush the uprising.

Elsewhere, Kallen, who had lost Lelouch in the break-in, made her way to the Guren. Lelouch, who was with Rolo, and who had unknowingly been beckoned to by C.C. in Lelouch's old Burai moments before, had escaped the fracas with his sibling. However, they were both ambushed by a lone Black Knights member. Lelouch shoved his brother out of the way of machine gun fire, the Black Knights member was killed in an explosion, and Lelouch fell several stories. After trying to contact Rolo unsuccessfully after the fall, Lelouch searched for him- while Rolo himself was talking with Britannian soldiers- and came across the old Burai again. He was confronted by C.C., but their talk was cut short as the commander shot her. Having Lelouch cornered, he and his men were set to execute him, but C.C. suddenly revived and kissed Lelouch, restoring his memories. Lelouch subsequently ordered the commander and his men to kill themselves, and soon met up with Kallen and Urabe, with Lelouch taking control of a Sutherland by Geassing its pilot soon after.

Calares, who had journeyed to the battlefield from the Chinese Embassy in a G-1 Base, sent a large group of Sutherlands, carried to the tower by VTOL craft, to put an end to the Black Knights. The Black Knights, though outnumbered, managed to hold their ground with the help of Urabe and Kallen's combat ability, and Lelouch's strategical acumen, until an anomaly appeared- the Vincent. The Frame swiftly tore through the Black Knights' ranks, causing Lelouch to panic. C.C., meanwhile, was placing explosives at the base of the tower. It was not long before the Vincent confronted Urabe, Kallen and Lelouch, easily evading Urabe and Kallen's joint strike with unnatural speed and moving to strike Lelouch's Sutherland down before Urabe blocked the blow and sacrificed himself to give Lelouch time. Thanks to Urabe's actions, Lelouch got the time he needed for the explosives to be put into place, and he detonated them, destroying the upper half of Babel Tower, with several Sutherlands being obliterated in the collapse and the G01 base being crushed, Calares along with it, when the upper half fell. Lelouch, C.C. and Kallen joined up with the surviving Black Knights in the lower levels, and used the fallen tower as a road to the Chinese Embassy.

Nightmare of Nunnally
In this manga spinoff, it is revealed that Zero provided the Japanese Liberation Front with resources to instigate this incident.