British Halloween

British Halloween (ブリテン・ザ・ハロウィン) refers to the events that occurred in the hours between midnight and early morning of October 18 of the current year of the timeline, where second Princess Carissa of the United Kingdom with the aid of the Knights of England launched a coup d'etat, seizing control of the country from her mother Queen Regnant Elizard. Despite the considerable gains of her coup in the early hours of October 18, the resistance forces led by the Anglican Church and with the aid of various other people including third Princess Villian, Kamijou Touma, and Acqua of the Back, pushed Carissa back and the knights to London, where the resistance made one final push against her culminating in the Battle of Buckingham Palace, where the people of London rallied under the banner of the Union Jack held by the Queen to stop Carissa.

The events refer not only to the fighting between Carissa's faction and Anglican Church but also includes the hostile actions perpetrated by Carissa's control of the armed forces against France, whom she thought was a threat against the country.

Called the English Civil War by the Western fandom of Toaru Majutsu no Index. It is the first major armed conflict in the story, a prologue of the much larger and longer World War III that starts soon afterwards.

Background
Rumors of a war between magic and science has been going on prior to the start of July of the current year of the timeline. Adding to that, the treaties signed by the United Kingdom that weakens its military capabilities, and the reliance of the country with Academy City, and the apparent weakness in the pacifism of her mother all gave Carissa a reason to take over the rule of the country to save it from ruin.

She dreams up a plan for her vision of the United Kingdom, after coming to a conclusion that England would lose all its value and even its people would be looked down upon by other EU nations, if the country continued on its current course. She decided that the most effective means of maintain England's honor and peace would be through military force through the use of the Curtana Original. However, Carissa knew well of the destruction that the Curtana, and likely replacement created, would cause as well as the present danger that a monarch in the future would abuse it. As such, she would rise as historical tyrant only to fall later but not before killing every British Royal family member that can use Curtana, sealing all the Curtanas, and any possible means of reviving them, becoming a sort of scapegoat for her country. With that, she hires New Light to search for the long lost Curtana Original, and has the Knight Leader and the Knights of England come to her cause of protecting the kingdom's honor and safety in their turbulent world, though keeping her plan of "tyranny" secret from her allies. Her fears are later exacerbated due to the increasing tensions between Academy City and the Roman Catholic Church, plunging the world to a war between science and magic, which would drag the country into ruin regardless of which side it will take.

However, despite the alliance, Carissa's relationship is weak, as the knights allegiance is held up by the Knight Leader, and is supported by her using Curtana Original and that her actions are beneficial to the country. Moreover, according to Index, the Knight Leader and Carissa act as mental pillars of support for the knights, and as such if one breaks down it threatens to collapse the knights' determination. Moreover, the three faction system that is part of the United Kingdom threatens the coup itself. As the royal family handles diplomatic relations with other countries, the knights only excel in direct fighting. Index predicts that since the Knight Leader has been defeated, Carissa's defeat will lead to the end of the coup without a leader to guide them.

Economic plan
Carissa and her force's economic plan relied on using ocean resources and the opening of ports again to allow transportation of goods from other countries that do not rely on air routes. Due to the suffering of the masses, Carissa's regime with the likelihood of being killed ensures that the people won't riot, a forced subjugation using military force no a national scale. In regards to oils and metals, Carissa planned to have undersea mountains surrounding the United Kingdom to mines, turning the barriers installed by the country to protect itself into large-scale mining facilities.

Prelude
The Curtana Original is later found by the start of July, though somehow do not deliver it to Carissa until October 17, though it is likely because they are unable to properly excavate it. Regardless, New Light delivers the sword to the Knight Leader on October 17, during the Sky Bus 365 terrorist incident and 5 days after the Eurotunnel bombing.

At this point, everyone in the British Royal Family suspects France and by extension the Roman Catholic Church in its involvement with the bombing, as for the Sky Bus 365, the family also France to have knowledge of the incident going to take place. Carissa in particular is just itching to take military measures against France and the Roman Catholic Church, only needing a justification to do so, as in genuine proof of French's involvement in the bombing of the Eurotunnel.

Beginning of the coup
Carissa, Knight Leader, and Villian, are in Folkestone in the terminal for the Eurotunnel with Index in order to investigate the bombing. After New Light delivers the Curtana Original to the Knight Leader's Skíðblaðnir, Carissa orders the knights to start the invasion, as her being of royal blood and having Curtana Original, the sword that decides the king, makes her the rightful ruler of the United Kingdom.

Takeover of the United Kingdom
On midnight October 18, the Knights of England including the country's police and military forces takeover castles and fortresses, religious establishments such as churches, hospitals and police stations, mints, and government buildings such as Parliament. In fear, people stay indoors, and those who are outside are then arrested. The police and the military would later be used to deal with civilians, gathering them up in large facilities like hotels and theaters, and would threaten civilians with getting shot if they left specified buildings.

Queen Elizard and Archbishop Laura Stuart notice that the knights are taking over Windsor Castle during their meeting, and immediately know it is Carissa's doing. The knights later break through the castle's defenses and capture them and the Curtana Second without meeting any resistance.

Resistance against the knights
Even at this point, Necessarius started resisting, however, they are apparently either ineffective or are simply overwhelmed by the surprise or sheer number of the knights, as with the case of the Agnese Forces. Those who resist would also be defeated quickly as the knights are empowered by the Curtana. Because of this, the Anglican Church forces decided not to waste unnecessary strength by forcibly bringing back their normal conditions. Instead, they were preserving their strength and waiting for a chance to strike back. The church knows they would lose if it came to a simple comparison of power, so they had taken the truly important items from the churches and cathedrals and gathered together to speedily evacuate while putting up local resistance. Meanwhile, the leaders of the majority of the Agnese Forces are later captured by the Knights of England in Edinburgh.

Witches have also been attacked by the knights as well. A notable group that has control of the Coven Compass later engages them in the Battle of Islay.

Threat against France
After the Index Librorum Prohibitorum's analysis of the ruined Eurotunnel, Carissa is able to determine with concrete evidence that a Roman Catholic faction in France was the cause of the "bombing". Carissa orders Knight Leader to have the Knights of England pressure the military to send a destroyer to Dover Strait in order to threaten France into the negotiating table.

She breaks the treaty of banning the use of the Bunker Cluster by ordering Knight Leader to arm the destroyer with the missile. She intends to have it aimed at Versailles Palace, where the Maiden of Versailles, the greatest intellect among the strategists that are behind the current political power of France, is residing. With Index's analysis adding legitimacy to her claims, Carissa intends to make the move a final warning for France. Moreover, Carissa knew of a French submarine with a nuclear missile aimed at London. It is likely that Carissa deployed the destroyer in hopes of not only deterring the French from attacking but also destroying the submarine.

Battle of Folkestone
Intending to end the coup early, the Amakus Christians commandeer a sea plane from Hyde Park and drop Kanzaki Kaori into Folkestone. Meanwhile, Carissa wants to remove the people who can use the Curtana Original, specifically her family, and intends to do execute her sister Villian, who went with Carissa and Index to investigate the Eurotunnel bombing. After Carissa finds out that Villian has escaped using a royal carriage after her servants determined Villian was in danger, she orders her knights to follow her as Villian makes her way towards Canterbury Cathedral in order to gain help from the Anglican Church. Before they can mount a hunting party, Kaori arrives before them after jumping off the sea plane. The Amakusa Christians would later land on a narrow river and temporarily makes the sea plane their base in Folkestone. Although no Amakusa Christians participate in the battle, they still release scouts in order to gain information against the knights.

The Knight Leader quickly defeats Kanzaki Kaori and battle, and rushes off with his knights to quickly catch up with Carissa again. Villian's carriage is later rejected from coming near Canterbury and is shortly destroyed, forcing Villian to meet with her sister again. With her capture, Carissa then orders her execution, which would've been successful if not for Acqua of the Back's timely arrival. Acqua of the Back makes his escape with Villian and has her ride his Bayard spiritual item to take her to a Necessarius hideout, the Amakusa Christians' seaplane. With no one left to hinder him, Acqua of the Back battles the Knight Leader, easily taking out the other knights with him. After a long battle against the Knight Leader and becoming injured for all his trouble, Acqua of the Back manages to defeat him. Acqua of the Back later comes upon the carriage where Index is kept and later fights more knights again. Touma, after sneaking into the knights' supply train to Folkestone, later arrives to find Acqua of the Back and Index. They later come upon Carissa who uses her Curtana Original to make a powerful explosion, forcing Acqua of the Back to save Index and Touma. After Acqua of the Back explains to Touma that he is in the country to stop Fiamma of the Right's plans, Touma and Index reunites with the Amakusa Christians and flee Folkestone.

Attack against France
Carissa would later receive a call from  the French president, asking that they should cooperate with regards to the terrorist attack on the Eurotunnel, though Carissa doesn't buy it and completely mocks his words. The president however after having enough of Carissa's insults, demands to know why she deployed a destroyer loaded with missiles in the Dover Strait, warning of the damage that it would cause to the relationship between France and the United Kingdom. Hearing this, Carissa marks the French president as a hypocrite as she says that she knows that there is a submarine hidden in Dover Strait which she assumes through the transmissions it has as French, and that it has a nuclear missile aimed at London, surprising the president.

Carissa later tells the president that her forces have noticed a submarine in Dover which is apparently aiming at London with a nuclear missile and that it is a French one. She threatens it by casually having her destroyer attack a bird, citing how they can easily kill one if they chose to do so. The president tells her that the submarine may just be a unaffiliated submarine, to which Carissa tests his bluff by having her destroyer attack the submarine claiming that since the submarine is a threat to her country then there'd be no reason for France to send it aid or rescue, lest she'll attack French cities with her destroyer.

Finally, Carissa mocks the French president for being unable to protect the lives of his people as a leader. The president remains silent, but then Carissa asks for him to just leave the decisions to the Maiden of Versailles, angering the president and ending their conversation. Due to Carissa's threats, it is likely that the submarine later sinks, making it the first military attack on France by the United Kingdom during the entire coup.

Overloading of Curtana Original
Despite her knowledge of the Amakusa Christians being in Folkestone, the loss of both Index and her sister Villian from her grasp, and the defeat of the Knight Leader to the now-injured Acqua of the Back, Carissa makes no attempt to attack them by herself or with her knights, apparently as a sign of ignorance. She later prefers to go back to Buckingham Palace in order to make readjustments on the Curtana Original. Seeing this opportunity, the Anglican Church forces, wanting to prevent the coup from being drawn out into a longer conflict, decide it is time to strike against Carissa in her most vulnerable state. After her losses in Folkestone, her already shaky relationship with the knights have already taken a blow due to the Knight Leader's defeat. Anglican Church forces hope that the knights will turn their backs on Carissa if she loses the Curtana Original, the only thing that determines the success of the coup. With that in mind, the Anglican Church forces make use of the very people she let get away, Touma, Index, and Villian, to do a mission to overload the Curtana Original.

Touma, Index, and Villian are chosen for the mission specifically because they cannot produce magic power as the knights have made a security measure on London that detects anyone who can produce it. Their mission is to have Villian interfere with the barrier in a subway tunnel in order to open up a branching track that goes directly underneath Buckingham Palace, allowing for a special railway car that has a magic circle on it to be the conduit for the Coven Compass spell, which the Anglican Church forces have been contacting, to overload the Curtana Original. The three later infiltrate London, dodging the knight's patrols with the help if Index, and later arrives in the station. After getting help from Misaka Mikoto, and opening the subway station, they are later joined by 20 ordinary servants of Villian. They later come upon the barrier, which transforms into the Mokkerkalfe, a giant made out of paper. After destroying it, they quickly leave as the special railway car makes its way into Buckingham Palace and Coven Compass fires it spell. Curtana Original later overloads, filling London with telesma, making it dangerous for anyone to use magic. As for Carissa, though she is injured and much of her and the knights' power have been lost, they are still a formidable foe. In spite of the threat posed by Carissa, the Anglican Church forces are now able to contend against Carissa now that she and her knights are weakened.

The Anglican Church forces scattered at the beginning of the coup would later rendezvous and consolidate in the outskirts of London, as well as prepare their magic and weapons as they wait for the telesma in London to dissipate before making their move.

Purging of the knights faction
Anticipating the assault on Buckingham Palace by the Anglican Church forces and the use of the mobile fortresses as well, Carissa, likely wanting to further her plans in destroying the codes and documents in the Palace that would allow for the construction of a new Curtana, deliberately refuses to move from her position in London. Anticipating them, Carissa further plays her role in looking like a tyrant. To prevent reprisals on the knights after she is defeated, Carissa "purges" the knights faction by making them think they have been severely injured by her, in the hopes of preventing them from falling apart, and consequently the country, as a whole, under the guise of retaining control over them due to their losing morale on Carissa's actions after the defeat of the Knight Leader and the overloading of the Curtana Original. She would later have them transferred to a location far from the battle that would occur in Buckingham Palace.

This however results in Buckingham Palace's security level falling, essentially making her the only one able to defend against the attack of the Anglican Church forces. Carissa's excuse for this is that she has the Curtana Original making guards useless for her. Without knights to patrol London, guard her, or to defend against the Anglican Church forces, Carissa orders the mobilization of almost 20 Griffin Sky mobile fortresses to her location.

Planning
Despite the edge they have now over Carissa, the Anglican Church forces are still aware of the power that Carissa wields. Prior to being able to enter London after the overloading of the Curtana Original, Anglican Church forces spend their time preparing for their assault on Buckingham Palace, as well as gather as much of their forces as they can, which eventually reaches to over 500 people. With the belief that Carissa's forces at are the brink of collapse, the Anglican Church forces hoped that the coup d’état would collapse if they are able to destroy the sword. The plan was to split the forces up into 20 groups of trucks and go toward Buckingham Palace as fast as they can in different routes, breaking through any kind of inspection points using magic spells.

Knowing of the difficulty of their situation with Carissa being a "non-standard" enemy, the Anglican Church forces include Kamijou Touma as part of their plan, as his right hand can destroy the Curtana. To aid in their attack on Carissa, the Anglican Church forces contact both the Coven Compass and Selkie Aquarium mobile fortresses to bombard Buckingham Palace and further weaken Carissa. The strategy was to use Touma as a slow-moving mobile cannon, where Kanzaki Kaori and the Amakusa Christians will bait Carissa towards Touma's direction in order for him to destroy Curtana Original. The Anglican Church forces however know that Carissa will immediately notice them the moment they enter London and attack them, hoping that the attacks would render her forces busy in defending themselves from the bombardment. before they could mount a "concrete" counterattack.

First phase of the battle
The Anglican Church forces charge toward London as planned, with Coven Compass and Selkie Aquarium bombarding Buckingham Palace with their large-scale flash spell. Despite this, the attacks are a mere nuisance to Carissa, who uses her Curtana Original to create dimensional debris to not only defend but to attack the Anglican Church forces as well. This prevents the Anglicans to quickly get to the palace, and they are also later forced to aid civilians who are caught in the attack by Carissa's dimensional debris. As a consequence to this, Villian is the first one to arrive at the palace. She later finds Carissa and gets into an argument with her, who is completely disinterested. Touma later arrives as well and then pushes Villian out of the way just in time before she could use her sword on her.

Without any ally he can rely on, Touma is forced to "entertain" Carissa, coming up against not only her but the Griffin Skies as well. Touma doesn't fare well at all in the one-sided fight. Anglican Church forces later arrive, with Kaori saving Touma before he is further harmed. Kaori then asks Index to analyze Curtana Original. Despite their superior number, the presence of a Saint, and their tactics in taking down the Griffin Skies, Carissa continues to dominate. This leads to Kaori to conclude that they truly need his right hand to destroy the Curtana Original. Touma agrees but warns that when he was against Carissa his right hand worked only a few times. Kaori tells Touma that he has a 1.25 second opportunity in negating the appearance of the dimensional debris in their world. In spite of the short time frame, Touma agrees and tells Kaori that he will wait for a good opportunity to strike. Kaori then tries to return to do battle with Carissa.

After fighting everyone on her own using her sword and the dimensional debris it creates, Carissa gets an opportunity to get to Villian. It is here that the Anglican Church forces are able to make some serious damage on Carissa. The Anglican Church forces used a combination of Villian's magic arrows fired from her bowgun and the large-scale flash spell of the Coven Compass to not only attack her but to recover their strength as well. Finally, Index uses Spell Intercept on one of the incoming large-scale flash bombardments of Coven Compass. It hits the Griffin Sky mobile fortresses and hits Carissa through an opening in Curtana Original’s defenses. Carissa is then caught in a tremendous explosion.

She survives, though is not unscathed by it. Carissa then orders the firing of a cruise missile with a Bunker Cluster warhead on Buckingham Palace, seeing that the Griffin Skies have been destroyed, forcing her to use the warhead earlier. Seeing the extensive damage that it would cause, not only on Buckingham Palace but in a considerable part of London as well, Kaori tries to use a large defense barrier with a 3 kilometer wide radius. Carissa later attacks her as she tries to create the barrier, though she is able to dodge it but the construction of her barrier is delayed. Kaori tries to create the barrier again. However, it is too late, the warhead splits and is able to get through the holes of the unfinished defense barrier. In spite of this however, 200 of the missiles exploded prematurely because of the barrier, sparing London. As the missiles were set by Carissa to detonate 5 meters underground, the missiles bury themselves into the ground before exploding in Buckingham Palace. Magicians present on the scene would later use defensive spells to weaken the destruction caused by the missiles that got through.

Second phase of the battle
Before Carissa can order another attack with a Bunker Cluster-equipped cruise missile, Riméa uses a mass communication spell in London and reveals Carissa's true motives for her coup and pleads to those who hear, specifically the knights and the Knight Leader, to save her. The knights, who have recovered from Carissa's "punishment", and the Knight Leader answers Riméa's call as well, using his magic to prevent another Bunker Cluster attack on them. He orders the knights to assist the fallen Anglicans while he engages Carissa in battle. Carissa tries to fire several Bunker Cluster missile attacks on Buckingham Palace in order to bypass his magic but is stopped by Acqua of the Back destroying the antenna that is used for military transmissions. From there, Acqua of the Back, the Knight Leader, as well as the recovered Kanzaki Kaori, does battle against Carissa in a clash of four swords. The three Saint-level magicians then fight Carissa, forcing her for the first time to be on the defensive. Despite this, Carissa manages to regain the offensive again by attacking the ordinary magicians and knights in order to ruin their synchronicity as a group.

Elizard however arrives just in time to relieve the forces against Carissa, fighting her own daughter herself with the Curtana Second. Elizard manages to hold her own with Curtana Second but it is clear Curtana Original still superior. With that, Elizard throws away her sword and uses the Union Jack spiritual item to distribute the power of the Curtana Original to the people of the United Kingdom and asking them through a communication spiritual item if they would like to help them save Carissa. Now with the aid of the empowered citizens in London, the magicians and knights present renew their attack on Carissa, who is too preoccupied in preventing the power of Curtana Original from being drained further. Because of this she cannot attack properly against them creating an opening for Touma after Index has finally finished analyzing it and used Spell Intercept on it to distribute its power. He has Acqua of the Back throw him towards her, and with his right hand, not only destroys the Curtana Original but punches Carissa in the face, finally ending her coup.

Aftermath
The conflict was the inevitable result of the manipulations of Fiamma of the Right on countries that are under the Roman Catholic Church's sphere influence. However for all the destruction it caused, it prevented the onset of a full blown conflict with France, a result that Fiamma of the Right originally predicted to happen in order for it to lay London in ruin and allow him to collect the external controller for Index's John's Pen. Fiamma of the Right is eventually able to collect the external controller from the ruins of Buckingham Palace himself immediately after the end of the conflict.

The coup only delayed a conflict with France as the declaration of war by Russia would be declared on the same day the coup ends and formally begins the very next day. The acts of the perpetrators of the coup would not be addressed until after the end of war as they are used for the defense of the country. Both the Knight Leader and Carissa would later partake key roles in the battle of Dover Strait.