I had thought humans to be wiser creatures...
The Third Gestahlian Campaign is a military conflict that dominates the World of Balance before the end of the world in Final Fantasy VI. The war lasts for two years and is fought mainly between the Returners, a small resistance group operating from the Sabre Mountains, and the Gestahlian Empire, which aspires to conquer the Northern Continent for world dominance. The war escalates as states sympathetic to the Returners are attacked by invading Imperial forces, and is eventually brought to the Imperial capital of Vector itself. The war comes to a halt when Kefka Palazzo moves the Warring Triad out of alignment triggering an apocalypse that wipes out both the Empire and the Returners. The First and Second Gestahlian campaigns supposedly take place 18 and 8 years ago, although the canonity of this is questionable.
Start of the WarEdit
According to the Settei Shiryou Hen guide book, the Third Imperial Campaign starts following a year of small-scale skirmishes between the Empire and the Kingdom of Doma. On the Southern Continent Maranda opposes the Empire with armed resistance, and is as a result burned to the ground by General Celes Chere. Little is known about the activities of the Returners at this point.
When a frozen esper is discovered in the Narshe Mines two years into the war, an Imperial task force sets out to capture it. In the ensuing Raid on Narshe the superiority of the high-tek Imperial Magitek Armor is demonstrated, but the raid fails when the esper kills the Imperial soldiers. Terra Branford is involved in the raid as a puppet controlled by the Imperial troops through a slave crown, and is released from its effect during the incident. Locke Cole of the Returners helps her escape from Narshe Guards, killing a guard and causing Narshe to close its doors to the Returners for the time being.
Terra is evacuated to Figaro Castle. When King Edgar of Figaro refuses to hand her over to the Empire, Imperial forces unsuccessfully attack Figaro Castle and occupy South Figaro. Imperial General Celes Chere deserts after witnessing the brutality of her troops, and escapes captivity with Locke's help.
Shortly after South Figaro is occupied, the last battle between Doma and the Empire is fought at the gates of Doma Castle. The battle ends when Kefka, acting against the direct instructions of General Leo Cristophe, poisons Doma's water source, eradicating all of its population except for Cyan Garamonde and one Doman Sentry. Having defeated its strongest opponent, the Empire reaches its height.
Turn of the TideEdit
Following the previous unsuccessful raid on Narshe, Kefka plans a bigger attack with the intent of seizing the frozen esper and destroying the town. Having laid the groundwork for a wider offensive by capturing South Figaro, a large Imperial force advances towards Narshe. The Elder of Narshe accepts the help of the Returners in defending the town and the esper, and together they inflict a remarkable and humiliating defeat on the Empire in the battle for the Frozen Esper. However, the Elder is reluctant to join the war on a wider scale.
The Returners raid and destroy the Magitek Research Facility in Vector, cutting off the Empire's supply of magic and dramatically altering the balance of power in the war. The Elder of Narshe agrees to join the Returners in a joint attack on Vector, but they lack the manpower to defeat the Imperial army. Terra is sent to the gate to the Esper World to negotiate an alliance with the espers, but as the gate is opened the espers go berserk and attack everything in sight. Intending to rescue their friends who were captured in an Imperial invasion of their world 18 years prior they set off for Vector, but when they find their friends are already dead they decimate the city. Helpless against the esper onslaught, the Imperial army retreats to the Imperial Palace and Returners and Narshe Guards peacefully occupy most of Vector.
Emperor Gestahl calls for a ceasefire and withdraws his forces from South Figaro and Doma as a gesture of goodwill. Now allied with the Empire, the Returners help negotiate peace between the espers and the Empire, which is an easy affair as both sides are ashamed of their previous actions. General Leo and Yura sign a peace treaty in Thamasa, hoping to bring an end to the bloodshed once and for all.
The Imperial surrender to the Returners is revealed to be a ruse. Imperial forces led by Kefka attack both General Leo's troops and the Returners before turning on the espers, transforming them into magicite. General Leo fights Kefka and is killed. Kefka and Emperor Gestahl enter the Esper World, reach the Warring Triad and use its power to raise the Floating Continent. Having been previously incapable of entering the Esper World, and oblivious of the existence of magicite, Emperor Gestahl's surrender was nothing more than a change of tactics; by controlling the Warring Triad, he could control the world from the Floating Continent without his Imperial Army.
The Returners set off for the Floating Continent and in the ensuing battle the Imperial Air Force is destroyed. With the last military branch of the Gestahlian Empire in ruins, the Returners rush to claim the Warring Triad. When they arrive, Emperor Gestahl explains his plan to control the world through the power of the Triad; with magic replacing Magitek, he no longer has a need for a military. Kefka moves the Triad out of its alignment, changing the delicate balance keeping the world in order. The Emperor tries to stop him, only to be tortured and thrown off the Floating Continent to his doom. The Returners escape as the continent breaks apart, witnessing the apocalypse shifting the face of the world from the air. Both the Gestahlian Empire and the Returners are mostly wiped out as a result.
With most combatants eradicated, the war de facto ends as the world shifts to the World of Ruin. Kefka absorbs the power of the Triad and uses it to dominate the world, destroying anyone who opposes him with his Light of Judgment. Kefka dominates the world for a year but is killed by the Returners in his tower.
With continents replaced by islands and several plants refusing to grow, the damage of the apocalypse is irreversible. Although the fallout of the Third Gestahlian Campaign will continue to torment the people as they start rebuilding the world, slow recovering is witnessed indicating the end of the world is at least partially reversible. The vanishing of magic and espers means history cannot repeat itself, guaranteeing a less insecure future for what remains of human life.