A Guild War (ギルド間抗争 Girudo Kan Kōsō) is a state of overt conflict between two or more guilds. Participating guilds usually fight with the desire to annihilate the enemy guild(s).
The Magic Council has forbidden Legal Guilds from having guild wars with each other.[1] Legal Guilds are allowed to declare war on Dark Guilds without fear of retribution from the Council.[2] In one instance, a Legal Guild retaliated against another Legal Guild as a means of self-defense[3] and after the Magic Council finishes their investigation, the Legal guild that instigated the guild war will be disbanded.[4]
Prior to these events, in X679, Guild Wars were common as Legal Guilds fought over commercial rights, land and establishments.[5]
Eventually, in X692 at the end of the Second Trade War with the humongous toll of death from warring feudal lords and guilds fighting over trading rights in the aftermath, the Magic Council has passed the Interguild Dispute Interdiction Treaty that forbids all and every guild from waging war against one or another for whatever reason, marking a beginning of a short era of peace.[6]
The Fairy Tail vs. Phantom Lord War is the main event of the Phantom Lord arc. It takes place in the year X784 with the purpose of capturing Lucy Heartfilia.[7] Sparked when Iron DragonGajeel Redfox destroys the Fairy Tail guild's building[8] and attacks the members of Shadow Gear,[9] the war starts at the Phantom Lord Guild where guild members of Fairy Tail led by guild master Makarov Dreyar attack Phantom Lord's guild and its mages.[10] However, Makarov is weakened by Aria's Magic,[11] forcing Erza Scarlet to order the guild members to retreat.[12] Phantom Lord later attacks the Fairy Tail Guild[13] but is subsequently defeated by the help of Natsu Dragneel and newly healed Makarov.[14] The balance of power in the Fairy Tail vs Phantom Lord Guild War implies heavily that Fairy Tail is significantly stronger than Phantom Lord. Gajeel Redfox is the strongest of the S-Rankers in Phantom Lord, surpassing the power of the Element 4. He is defeated in battle by Natsu Dragneel, who is not even recognised as S-Rank by Fairy Tail. Furthermore, Phantom Lord was defeated by a Fairy Tail that lacked Gildarts and Laxus. Laxus for example is far more powerful than Natsu, and is later proven to be capable of defeating wizard Saint Jura, who held the number 5 wizard saint position at his defeat in the Grand Magic Games. It is possible that Laxus is stronger than everyone -including wizard saint Jose- in Phantom Lord. Gildarts by extension is even more powerful than Laxus, though at this point in time, he is away on a 100-year quest and is yet to return. It is highly probable that Gildarts is more powerful than Jose Porla. Makarov Dreyar is the most explicitly superior mage to Master Jose. The final battle sees Jose defeated in a single, devastating strike by Makarov, proving Fairy Tail has in fact overtaken Phantom Lord to become the most powerful guild in Fiore.
The Fairy Tail vs. Grimoire Heart War is the main event of the Tenrou Island arc. It takes place in the year X784 when Grimoire Heart interrupts the Fairy Tail Guild's S-Class Mage Promotion Trial to find the Dark Mage Zeref.[33] During the first part of the war, Makarov Dreyar is incapacitated by Grimoire Heart Guild Master and former Fairy Tail Master Hades[34] while the Seven Kin of Purgatory lead the attack on the island.[35] However, the Seven Kin of Purgatory are subsequently defeated by the Fairy Tail Mages. Grimoire Heart Deputy Bluenote Stinger also joins in the fray[36] but is defeated by Fairy Tail Ace Gildarts Clive.[37]Team Natsu, Wendy Marvell and the Exceeds then battle Hades[38] with Laxus Dreyar joining in partway through the fight.[39] Hades pushes the Fairy Tail Mages to their limits and was on the verge of victory until the Exceeds destroyed his power source to give Natsu the chance to defeat him.[40] However, this war leads to the reawakening of Acnologia[41] which subsequently leads to the seven year disappearance of the Tenrou team.[42]
The Fairy Tail vs. Tartaros War is the main event of the Tartaros arc. It takes place in the year X791 when Tartaros massacres the Magic Council, and proceeds to assassinate former council members.[43] One of their members, Tempester, happens to cross path with members of Fairy Tail while on a mission to kill Yajima, a former member of the Council.[44] Their battle results in a Pyrrhic victory for Fairy Tail, as all members of the Thunder God Tribe are critically injured, leading to the proactive movement by Fairy Tail to save the former council members and thwart Tartaros's plan.[45] With the exception of Natsu's team, all attempts to subvert the assassinations fail, with Erza, Mira, Elfman, Liza and later Natsu falling into Tartaros captivity. Elfman is coerced into planting a bomb lacrima 500 times more powerful than a jupiter cannon inside Fairy Tail with everyone still inside. The guild is annihilated, however all the members of fairy tail survive due to a fast acting Cana, who imprisons every member of Fairy Tail using her card magic, and having the exceeds fly the cards to safety. The exceeds carry the guild members in card form straight to Tartaros' flying fortress, where the counter-attack begins. The Twin Dragons of Sabertooth assist the war on Fairy Tail's side, to retrieve Minerva and bring her back to Sabertooth. The war with Tartaros eventually marks Fairy Tail's responsibility for the destruction of all 3 pillars of the Baram Alliance.
The Lamia Scale vs. Orochi's Fin is one of the events of the Avatar arc. In X792, Orochi's Fin launches a monumental assault against Lamia Scale and Margaret Town during the aftermath of the Thanksgiving Day parade, when they are at their most vulnerable state.[46] At that time, Lamia Scale has the help of former members of the Fairy Tail, as Lucy Heartfilia, Natsu Dragneel and Happy. The war concludes when the ace member of Orochi Fin, Bluenote Stinger, is defeated in an overwhelmingly destructive assault by Natsu Dragneel.