Battle at the 'Mausoleum of Eighty-Eight Emperors'

 is an event that happened in Code Geass: Lelouch of the Rebellion R2.

Prelude
Following their devastating defeat at the Battle at Xiaopei, the remaining Black Knights made a hasty retreat underneath the 'Mausoleum of Eighty-Eight Emperors' in an attempt to lure the Chinese Federation into a one-sided battle (assuming that the Chinese Federation wouldn't launch an attack on a sacred area). The High Eunuchs however turn against Li Xingke's faction (taking Zhou Xianglin and the rest of his faction that was onboard the Longdan prisoner), as they have already called upon the assistance of the Holy Empire of Britannia to help them kill the Empress and defeat any oppositions. Zero then told Diethard Reid to get their plan ready, as time draws near for battle. However, the Black Knights didn't know about the High Eunuch's plan until the Chinese Federation Air Force started to bomb the Mausoleum in an attempt to wipe them and Empress Tianzi out.

Battle
Li Xingke was devastated to see the High Eunuchs violate the sacred Mausoleum for their petty ambitions and ordered all forces to cease fire as the Empress was in there, but the High Eunuchs considered the Mausoleum as a perfect burial site for the Empress, as it serves as the burial grounds for the past generations of emperors. They also stated that they already set up a "puppet bride" to replace her (so that the bride could be married in a political marriage to First Prince of Britannia, Odysseus eu Britannia). Hearing this, XIngke and his Shen Hu charged at the High Eunuchs, only to engage in battle with Gino Weinberg and his Tristan (GIno stated that he was upset at Xingke for capturing Kallen and her Guren before he has a chance to settle some unfinished business with her). At the same time, Kyoshiro Tohdoh deployed his Zangetsu into battle followed by Chiba's and Asahina's Akatsuki Command Model Zikisans. Tohdoh stated that their (the Black Knights) air power is limit and to strike at the enemy with "courage and strength."

C.C. also got into her Akatsuki Command Zikisan (pink-colored), as Zero told her to have an escape route ready in case they lose, but she was confidant enough that they wouldn't lose if he (Zero) comes up with a smart "trick." This is when the Chinese Federation send the second wave of aircrafts to attack.

Tohdoh, Chiba, and Asahina dodged the attacks launched by the VTOL Gunships, and launched a ferocious counterattack, taking out a large number of the opposing aircrafts. Seeing Tohdoh in action, Gino stated that he was surprised someone that was as strong as Kallen from within the Black Knights. Suzaku Kururugi told Gino that he would handle him and deployed his Lancelot Conquista into battle, followed by about a dozen of the new Vincent Wards (which C.C. saw and had doubts about winning this battle). Meanwhile, Hong Gu and the rest of Xingke's forces saw the Mordred landing right next to them and feared for the worst. Anya Alstreim acted without hesistation and her Mordred attacked the Gun-Rus with her multiple missile system, destroying some of them. Hong Gu then ordered all remaining units to surround her from three sides and attack simultaneously, which turns out to be useless as the Mordred defended itself with its Blaze Luminous system. Xingke broke off the engagement and attempts to break through the Mordred's shields, but was once again cut off by the Tristan. The Avalon sits back, unwilling to engage the enemy, and instead serve as a support ship throughout the entire battle (Nina Einstein asked if the Mordred's Stark Hadron Cannon could demolish the Mausoleum. Lloyd Asplund answered that it would, but Kanon Maldini (Schneizel's right-hand man) warned that if they do so, it would spark nationwide outcries against Britannia if they killed the Empress and that it's up to the High Eunuchs to deliver that last "mortal blow").

Zero then talked to the High Eunuchs, as they boastfully and foolishly revealed their plans (to have the new Empress marry Odysseus in a political marriage, sell their land and people to Britannia, and in return, gain the title of Britannian nobility). As they were discussing their plans, the battle rages on: the Shen Hu fights a equal, yet hopelessly-looking battle with the Tristan; the Mordred continues to decimate Xingke's forces (Hong Gu survived the battle); the Zangetsu holds its ground against the Lancelot Conquista (who at the same time, attacked the Akatsuki units that were performing anti-air attacks on the ground), as C.C. (who was recently cut off from Tohdoh by Suzaku himself), Chiba, and Asahina fight off the Vincent Wards and the Chinese Federation Air Force. The High Eunuchs laughed at their "wonderful scheme," as the debris of the Mausoleum came crashing down on the Ikaruga, damaging the shielding system that was protecting the deck of the ship. Empress Tianzi ran up to the deck of the ship despite warnings by Kaguya Sumeragi, and pleaded for all forces to cease the fighting. Xingke, seeing the endangered Empress, raced to her, but his Shen Hu lost one of its four "wings" when the Tristan use its Slash Harkens to knock it off. Seeing the Empress on top of the ship, the High Eunuchs ordered all of their Gun-Rus to focus all fire on the Empress herself. Seeing this, the Shen Hu covered the Empress and used its rotating slash harkens to shield her, despite taking heavy damage. Xingke urged the Empress to run away, but she was unable to because of: (1) her feelings for Xingke AND (2) there was so much firing that there could be danger that she would be struck if she moved from her position. Xingke pleads for someone (didn't care who) to save her. Zero responded with his Shinkiro as cannon fire from both the Longdan and the Gun-Rus nearly destroyed them all.

Turning the tides of the battle
Second Prince Schneizel el Britannia looked on from the Avalon, only to see the Shinkiro defending the Ikaruga and everyone in and on it from harm. The High Eunuchs were frightened to see an unfamiliar Knightmare defending both Xingke and the Empress. Zero then send a warning to both the Britannians and the Chinese Federation about the consequences of fighting on. Everyone on both sides were shocked to see Zero engaging in direct combat, but the High Eunuchs insisted in fighting on, ordering all cannons to "press home" their attacks. Zero then had the Shinkiro use its powerful shielding system once again to defend his comrades from harm with little effort (the newest and most powerful shielding system in the world, as stated by Rakshata Chawla, shocked Nina, Lloyd, and Cecile Croomy. Lloyd stated that they (Britannians and Chinese Federation) might have lost the battle). The Shinkiro then opened up its chest and fired the "Zero Beam," which wiped out a large number of enemy Gun-Rus simultaneously, severely damaged the Longdan, and damaged the Mordred's right arm and shoulder despite having its shields up. Gino then ask Schneizel what to do next, as Schneizel watched anxiously on what Zero was planning next. Zero confidently told Xingke that strategies, not tactics are what used to win battles.

Back in the Longdan, the High Eunuchs received a alarming message from the Vermillion Forbidden City that there are riots have broken out throughout the Chinese Federation, as people rise up everywhere (it turns out that Zero's main plan was to have Diethard hacked into the Chinese Federation communication systems and record the message between Zero and the High Eunuchs). Onboard the Avalon, Cecile replayed the message to everyone onboard. Zero then admitted he used Xingke initial coup de tat (see http://en.wikipedia.org/wiki/Coup_d'état) as an initiative to have the people rise up against an oppressive government. Now that they know that the people on their side, the Black Knights continued the fighting, with the Zangetsu taking out the last Vincent Ward and, C.C. and Chiba attacked the flying Mordred (with its shields up). Before Anya got the chance to counterattack, both she and C.C. experience strange telepathic visions of Lelouch's childhood, which distracted Anya from keeping her shields. Asahina then took the chance to strike the Mordred's float system, causing it to crash head-first into the ground. Suzaku was unable to help her out as he continue to fight Tohdoh. Gino announces that he's going in to cover the Mordred, as Zero deployed the rest of the Black Knights' Akatsukis to attack the remaining enemy forces. Onboard the Avalon, one of Schneizel's subordinates stated that they could bombard the enemy from the air to destroy them, but Schneizel stated that they're withdrawing, stating that the High Eunuchs lost the people's support and that they're no longer worthy of being representatives of the Chinese Federation. All three Knights of the Round (Gino, Anya, and Suzaku) withdraw along with the Avalon. The High Eunuchs' forces hastily retreated as the Shen Hu and the Black Knights pressed their pursuit. Xingke broke into the Longdan, executed the High Eunuchs, and rescued Zhou Xianglin and his comrades. Zero also entered into the base to rescue Kallen Kozuki but Zhou stated that she was transfered out, along with her Guren, and handed over to the Knight of Seven (Suzaku Kururugi). Angered, Lelouch sweared that one day that he would rescue Kallen, but not now as he had other matters to deal with.

Conclusion
The Empress and Li Xingke's factions reunited with each another onboard the Ikaruga. At that time, they formed an alliance with the Black Knights and went out to defeat any opposing factions/separatist movements that would try to take over the government. They made the Empress the true ruler of the newly formed United States of China and are progressing on forming an alliance with all Asian countries that are either neutral or are part of the Chinese Federation. This would form the basis for the formation of the U.F.N. Attempts were made by the Britannians to annex at least half of the former Chinese Federation through threats and negotiations, but failed miserably.

Reference

 * When Shen Hu Wins Glory
 * Power of Passion
 * Love Attack!