Guild War

A Guild War is when two or more guilds simply declare war on each other and try to exterminate each other. The Magic Council has forbid the legal guilds to have guilds wars to have guild wars. The council has also forbid any members of the Ten Great Holy Mages from fighting each other to avoid a cataclysim. Noteably, the legal guilds are apparently allowed to declare war on Dark Guilds without fear of retribution from the council.

War on Zeref
According to the council, in ancient times, the wizards went to war against the dark mage master Zeref and in the end, they managed to seal him in a multi-lock prison because he was too powerful tobe killed. The exact details of this war are unknown.
 * Participants: Wizards against Zeref
 * Notable Players: Zeref
 * Outcome: Zeref is sealed away.

Fairy/Phantom War
After Lucy Heartphilia joined Fairy Tail, Phantom Lord master Jose was hired to by Mr. Heartphilia to bring her back home. However, Jose used this as an excuse to finally get his "revenge" on Fairy Tail and thus he began to instigate a Guild War. After pushing Fairy Tail master Makarov to the limit, Makarov declared war on Phantom Lord.
 * Participants: Fairy Tail Guild against Phantom Lord Guild
 * Noteable Players: Makarov, Natsu Dragonil, Gray Fullbuster, Erza Scarlet, Mist Gun, Jose Pola, Gazille Reitfox, Elemental 4
 * Outcome: Phantom Lord loses and is dissolved

During the battle, Makarov's magic was drained by Aria after Jose used a cheap trick and leadership of Fairy Tail fell on Mirajane, Kana Alberona, and Erza. As Phantom's robotic guild attacked, Natsu, Gray, and Elfman went inside and defeated the Elemental 4 with Erza's help. However, Jose's arrival spelled defeat for them. In a friece battle, the two Dragon Slayers Natsu and Gazille battled to end the war with Natsu as the victor. Despite losing his best men, Jose still wouldn't surrender. When all hope seemed lost, Mist Gun retrieved all of Makarov's lost magic and destroyed all of Phantom Lord's subdivisions thus allowing Makarov to return and use Fairy Law to defeat Jose and win the war.

After the war, the council tried both Makarov and Jose over the war and damage done and they, begrudingly, only ruled in Fairy Tail's favor on the grounds of self defense. For instigating the war, Jose was stripped of his Saint Wizard title and Phantom Lord was dissolved.

Fairy Tail Civil War
Luxus's angry with the care free Fairy Tail wizards reached its peak and he declared a civil war to make himself the Guild Master. After Evergreen turned a number of women to stone to act as hostages, Luxus announced the rules of the battle and thus systematically forcing the mages of Fairy Tail to fight each other while Makarov, and Natsu and Gazille surprisingly,couldn't do anything to stop it.
 * Participants: Fairy Tail wizards against Fairy Tail team Raijinshuu
 * Notable Players: Natsu, Gazille, Mist Gun, Luxus Dreher, Team Raijinshuu
 * Outcome: Natsu defeats Luxus and Luxus is excommunicated for instigating a fight and threatening innocent people.

As Natsu and Gazille helped free Erza (and promtly recieving a beating for touching her) she finds and defeats Evergreen which frees the other hostages. Not to be outdone, Luxus activates the Hall of Thunder spell to keep the balance of power in his favor. Lucy then finds and defeats Bixlow with Loki]'s help. After this, [[Lluvia Loxar, and Kana are defeated by Raijinshuu captain Fried Justine and Mirajane reawakens her lost powers to make him reveal his hatred for Luxus's plans. With this, he surrenders and Luxus is left with no one to defend him.

Having enough, Mist Gun arrives to talk sense into Luxus, but as he sees there is no hope for him, he engages him in combat and appears to match him. However, once Natsu and Erza arrive and his mask is blown off, he leaves the fight to Natsu as Erza goes to destroy the Hall of Thunder with the other Fairy Tail members help. Natsu is sooned joined in his battle with Luxus by Gazille and as they battle him, they discover Luxus's horrible secret: Artifical Dragon Slayer powers. As Luxus uses Fairy Law to a failed outcome, Natsu enraged pummels Luxus into submission and becomes the strongest mage in Fairy Tail.

As everyone healed and prepared for the Fantasia Parade, Luxus was judged by Makarov for the civil war. For indangering not only the lives of his comrades, but the people of Fiore, Makarov excommunicates Luxus from the guild. Before he left, the whole guild showed the now hubbled Luxus that no matter how much of a jerk he is/was, they will always look out for him.

Light Guild/Balam Alliance War
Wjile not an official war after the council's dissolve and the raise of the Dark Guilds, the four most powerful legal guilds formed an alliance to stop them with full consent from the ne council. Delegates from Fairy Tail, Blue Pegasus, Lamia Scale, and Cat Shelter have banned together to destroy the smallest dark guild in the Balam Alliance, Oracion Seis.
 * Participants: Fairy Tail, Blue Pegasus Guild, Lamia Scale Guild, and Cat Shelter Guild against Balam Alliance
 * Notable Players: Light Team, [Oracion Seis]], Gerard
 * Outcome: Pending