The Crusades is a hundred-year war between Gears and humanity, led by the Sacred Order of Holy Knights, that began with Justice's awakening in 2074 until she was finally sealed away in 2175. When the Crusades at last came to an end, humankind was victorious, but no part of the planet was spared its ramifications.
Following the creation of Gears by That Man's Gear Project, the United States of America began to mass produce Gears in 2065—designed to be little more than slaves, incapable of independent thought—and to deploy them to allies across the globe, bringing countless other lands under its control. In 2073, That Man, secretly opposed to their use in war, thus decided to create a Gear that could command it own kind to stop the wars, whom he named Justice. In 2074, an incident occurred, however, which caused Justice to forget her identity and resulted in the destruction of Japan.
Justice thus "awakened" and, announcing herself to be self-aware, took command of all Gears across the globe, gathering an army, and declared war on all mankind. With little documentation of the truth of his research, That Man—his identity unknown due to joining the project under an alias—was widely believed to be the one pulling the strings behind the scenes since he had created Justice. Called "That Man" because no one knew where the blame really lay and his intentions were unclear, That Man was labeled a war criminal who had intentionally turned Justice against humanity.
In wake of heavy initial casualties, humans put their differences aside and formed the Sacred Order of Holy Knights to combat them. Immediately following the disappearance of Japan, America turned into a battlefield and suffered massive damage, such as New York being destroyed. The conflict was then centered around Russia and her neighboring European nations, but the fighting quickly spread, and the war soon engulfed the entire planet. The overwhelming power of the Gears brought humanity to the brink of extinction. Victims from around the world would seek refuge in Australia. For a time there was a period of stability and peace in the region, but eventually Gears gradually began to drive people away until mankind was forced to ultimately abandon the continent. The Tasmanian Islands then became a headquarters of operations that created a perimeter, not letting any Gears enter or exit.
At one point, hundreds of Gears laid siege to Rome, backing humankind into a corner. When things were at their grimmest, a bolt of lightning—to be later named St. Elmo's Fire—struck the Gear horde. It saved several members of the Holy Order, gave them the advantage and ultimately allowed mankind to triumph.
One notable event was the sealing of Hydra, a Megadeath-class Gear that attacked and destroyed London in under an hour. The Order's forces were unable to defeat it, and it rampaged for a day and a night, until Commander Kliff Undersn arrived and fought the beast single-handedly for seven days and nights. He successfully managed to sever three of its five heads and other limbs. Unable to spare more time on finishing off the massive Gear, the Order sealed the Hydra away.
During the Crusades, mankind's desire for a brighter tomorrow was so strong it resulted in the creation of a Magical Foci after their emotions were focused on a single "object", the Backyard. The Backyard interpreted this as an error that would destroy the world. To overcome the crisis, it sealed that conscious away in a single human's body, placing within I-No all the irregularities. She was discovered by The Original, who saw that her godhood was nigh and decided that she was a threat. His solution was to rid her of human desire, taking away her power and her sense of self, but the Universal Will punished him[source needed] and made him I-No's "other half", formed of mankind's wishes. Also during the war, That Man appeared in many different times, places and disguises, being responsible for the destruction of Baiken's colony; in truth, these appearances were that of the corrupted Original who wreaked havoc by possessing people in his spirit form while calling himself "That Man."
A pivotal event was the Battle of Rome (ローマ会戦, Rōma Kaisen?) in 2173, in which a horde of about 200 Gears attacked the city. The local army tried to fend off the menace, and sent a distress call. Despite Order headquarters telling to wait for reinforcements and the mission amounting to suicide, battalion captain Ky Kiske responded in hopes of ensuring the safety of its citizens. They resisted until 15 minutes were needed for everyone to be safe; due to soldiers reaching their limit, the Order began its retreat. In one outcome, Ky was killed trying to ensure that the civilian I-No was safe, and telling Sol Badguy to become the Order's next commander. Upon seeing the future ramifications (the war lasting until 2181, Dizzy taking over Justice's place, and humanity to be eradicated) and meeting That Man, I-No went back in time and ensured that Ky lived, later succeeding Kliff as the Order's commander.
In 2175, the war came to an end with the sealing of Justice (ジャスティスの封印, Jasutisu no Fūin?), with humankind finally victorious through the combined efforts of the Holy Order and Sol Badguy. In one account, Kliff challenged Justice to one last battle; upon Kliff's defeat, Ky stepped in to save the former commander and fought Justice for the first time. Forced to retreat, Justice found herself before Sol, and they fought evenly. During the fight, Justice learned that Sol was a Gear after breaking his headband, but his immunity to being controlled took Justice by surprise and Sol was able to defeat her. Ky, following her trail, found her weakened amidst lava and flames and ordered all support units to engage and seal Justice away in an impenetrable dimensional prison.
In the aftermath, most of the masterless Gear were rounded up and destroyed, and certain Gears—having entered a dormant state—were sealed and safeguarded for their worth as data. Those that gained self-consciousness of their own went into hiding at Ganymede, and most national leaders called for Gear research to be terminated immediately. From 2176 onwards, the day Justice was sealed into her dimensional prison would be used as the date for the Sanctus Populi's Celebration of Victory.
- At least, Ky Kiske, Johnny, May and the other girls, Zato-ONE, Millia Rage, Venom, and Baiken are orphans because of the war.
- As a result of the war, many people sought refuge in larger urban areas.
- In General Education, the subject of History is largely divided into two sections: pre and post-Crusades (there are a lot of anecdotes of what happened during the war).
- Many attribute the Nigel Famine to the excessive magic disposed during the Crusades.
- The conflict is implied to have begun on September 2, 2074 (the day of Justice's self-proclaimed "birthday") and to have ended on November 20, 2175 (the day the celebration of victory implicitly falls on, per Revelator Episode Mode dates being set prior and up to November 18, having less than 52 hours to settle, and the date being quite close to America's Thanksgiving holiday, which can occur from November 22 to 28).
- [GGWorld - "Gear"]
- Guilty Gear Xrd -Sign- script § "Philosopher B"
- Guilty Gear manual, pg.2
- Guilty Gear Complete Bible, pg.96-99
- Guilty Gear Xrd -Revelator- script § "Cause A"
- Guilty Gear script § "Sol"
- Guilty Gear Xrd -Sign- script § "Kaleidoscope B"
- [GGWorld - "Crusades"]
- [GGWorld - Timeline]
- Guilty Gear 2 -Overture- Lore § "The Crusades"
- Guilty Gear -Strive- script § "Confrontation"
- Guilty Gear 2 -Overture- Lore § "That Man"
- [GGWorld - "International Affairs"]
- [GGWorld - "Neo New York"]
- [GGWorld - "Australia"]
- [GGWorld - "St. Elmo"]
- Guilty Gear Xrd -Sign- script § "Devastation B"
- Guilty Gear X Lightning the Argent, pg.??
- Guilty Gear Xrd -Revelator- script § "I-No"
- Guilty Gear -Strive- script § "Prologue"
- Guilty Gear -Strive- script § "Omen"
- [GGWorld - "That Man"]
- Guilty Gear XX Drama CD Red script § "Temptation"
- Guilty Gear XX Drama CD Red script § "The Order's Oath"
- Guilty Gear XX Drama CD Red script § "Seed of Hope"
- Guilty Gear XX Drama CD Black script § "???"
- Guilty Gear XX script § "Report ♯6661"
- Guilty Gear XX script § "Last battle"
- Guilty Gear 2 -Overture- script § "The Unyielding Silhouette"
- Guilty Gear 2 -Overture- script § "Cynical Wise Man"
- [GGWorld - "Celebration of Victory"]
- [GGWorld - "Architecture"]
- [GGWorld - "Culture and Education 2"]
- [GGWorld - "The Nigel Famine"]
- Guilty Gear Xrd -Revelator- script § "May"
- Guilty Gear Xrd -Revelator- script § "Johnny"
- Guilty Gear Xrd -Revelator- script § "Leo"
- Guilty Gear Xrd -Revelator- script § "Identify A"