The Battle of Islay is the earliest known battle to have been fought during the British Halloween. It was fought between witches of the Coven Compass and the Knights of England in the Atlantic Ocean near the island of Islay.
The British Halloween had just begun and the Knights of England had started taking over several institutions in the country, including churches. With the witches of the Coven Compass allied to Anglican Church, it is likely the Knights of England attacked them in order to prevent the use of the Coven Compass.
First phaseEditDespite the witches' maneuverability with their flight, the witches of the Coven Compass knew that they were sorely outclassed by the knights that had been empowered by the Curtana Original. Smartvery suggested that they should have the Coven Compass advance outside of the United Kingdom's borders, farther from the island, as the Curtana Original's empowering effects on the knights only work inside the country's borders. 
Here, 100 witches were led by Smartvery to try to lead the knights farther to the sea. However, they were intercepted by 100 knights coming out of the water, forcing the witches to attack. The knights also brought a sea fortress with them.
Overloading of the Curtana OriginalEdit
- Main article: Overloading of the Curtana Original
Prior to 2:30 AM, Anglican Church forces contacted the Coven Compass in order to use its large-scale flash spell on Buckingham Palace as part of a mission to induce an overload in the Curtana Original.
Despite still being in a battle, the Coven Compass fired its large-scale flash spell on Buckingham Palace with the assistance of the "relay-points" set up by the Anglican forces across the country in order to guide the massive amount of magic power. The mission was successful, with Curtana Original overloading and severely weakening Carissa and the knights, likely a contributing factor on how the witches were able to turn the tide of the battle to their favor.
By 3 AM, the resulting battle had damaged the fortress and made it tilt due to the damage to its altitude control. In spite of this, it was still fully functional. The knights however incurred far much greater losses from the battle, with their sea fortress half sunk after having its sailing ability destroyed.
With the witches successfully leading the knights northwest into the sea outside of the country's border, they were able to successfully counterattack the de-powered knights. Despite the presence of knights still attempting to bring the Coven Compass down, the witch continued to protect it. Thus, the battle had essentially already been won.
With no apparent opposition from the knights, the witches were able to follow through with the Anglican Church's request of firing directly towards Buckingham Palace, using the Coven Compass' large-scale flash bombardment as the opening attack against Carissa for the Battle of Buckingham Palace.
- ↑ 1.0 1.1 1.2 Toaru Majutsu no Index Light Novel Volume 17 Chapter 4 Part 1
- ↑ 2.0 2.1 2.2 2.3 Toaru Majutsu no Index Light Novel Volume 18 Chapter 7 Part 2
- ↑ Toaru Majutsu no Index Light Novel Volume 18 Chapter 6 Part 9
- ↑ 4.0 4.1 Toaru Majutsu no Index Light Novel Volume 18 Chapter 6 Part 3
- ↑ Toaru Majutsu no Index Light Novel Volume 18 Chapter 6 Part 10
- ↑ Toaru Majutsu no Index Light Novel Volume 18 Chapter 7 Part 1
|British Royal Family Arc