The Crusade of the Seven Heroes is a conflict occurred prior the events shown in Overlord. The crusade was started by a fellowship of heroes as a form of revolt against the evil rule of the Second Overlord, who at that time was the dark master of all known lands of the world. The war ended when the heroes managed to destroy the minion horde and kill the evil sovereign, although it proved to be a victory paid at a dire price: the heroes' very souls.
In the distant past, the world was ruled by a single undisputed sovereign, the Second Overlord, a man whose wickedness and cruelty was legendary among all peoples and races of the land. Such was his evilness that his subjects could no longer suffer his dark dominion over them and thus they decided to rebel against his rule in order to overthrow his power. The one who started the rebellion was a man of extraordinary magical abilities simply known as the Wizard. The Wizard traveled between various kingdoms and regions of the world, seeking valiant warriors and adventurers willing to join his crusade against evil and rebuild their world anew, based on healthy principles and moral beliefs that guarantee the welfare of the population and not its oppression.
Finally he found six people willing to follow him:
- Melvin Underbelly, the Halfling
- Oberon Greenhaze, the Elf
- Sir William the Black, the Paladin
- Goldo Golderson, the Dwarf
- Jewel the Thief
- Kahn the Warrior
Together these seven prodigious warriors formed the legendary brotherhood known as "The Seven Heroes", the only known organisation/group ever formed in the history of the world to hold members of each of the sapient races within it. During the course of their adventure they also met an eighth person willing to join their group, a human champion of great physical strength and command ability, but is not known much about him.
Together the seven heroes freed all the Overlord's domains from his control through many epic clashes and battles. The climax of the conflict occurred in the Dark Tower, the Overlord's seat of power, where they battled fiercely against the minion horde and finally made it to the throne room, where the Overlord was cornered. The conflict proved to be devastating for the Second Overlord's forces, in fact only a little over a dozen minions out of an army of tens of thousands succeeded in surviving the wrath of the vengeful heroes. The war finally ended when, during his last stand, the Overlord was grabbed by the 8th Hero and thrown down from the Tower with him. It was a triumphant victory for the heroes, who succeeded with the sacrifice of their companion to ensure a prosperous and peaceful future for their peoples.
However, the happiness of victory was unfortunately short-lived. With his last, dying breath the Overlord casted a terrible curse on them, condemning the heroes to be corrupted by the seven deadly sins, so that in the future they would become as evil as him. The heroes did not put too much weight on the evil man's words, but the effects of the curse were already visible on them, through subtle changes in their personality and behavior. The most obvious evidence of this was when they discussed what to do after seeing their comrade, the 8th Hero, fall from the tower. They could have tried to help him or even just check if he was still alive, but no one did, blinded by their desperate desire to return to their respective homelands and be acclaimed as saviors by their peoples. Finally they plundered the dark tower of its riches, taking away any object considered valuable, such as money, magic pillars, smelters and etc, and destroyed everything they couldn't take away.
Thanks to the fame obtained from their victory over the evil Overlord, the heroes were rewarded by their peoples with prominent positions in their respective homelands, and some of them, such as Melvin Underbelly and Goldo Golderson, also succeeded in being crowned kings. This new world created by the heroes seemed to offer to the former subjects of the Overlord a new age of peace and tranquillity, with no more misery, suffering, and slavery. But, unfortunately, this is not the case.
Even though his corpse was rotting under the ground, the Second Overlord's spirit was still active and intent on getting revenge on his killers. He cheated death by taking control of the Wizard's body and driving his soul into oblivion. He then made all the heroes fall victim to their own personal vices through his evil influence and his venemous words, causing each to represent one of the seven deadly sins, just as he had previously prophesied with his curse. Little by little all these valiant heroes in shining armor became corrupt and cruel tyrants, indifferent to the suffering of their people and interested only in meeting their basest desires, just like their old enemy. Oh, the irony.
Meanwhile in the Dark Tower, not knowing of the plan put into motion by his deceased master, Gnarl decided to took matters into his own hands: after discovering that the 8th Hero was still alive, he saw him as a potential successor to the Overlord's throne and had the minions revive him by putting him into a magic sarcophagus in the Crypt in the Dark Tower's foundations. After some years, when he was awakened and wiped out of his memory, Gnarl crowned him Overlord and told him how his predecessor was killed by the Seven Heroes to give him a desire for revenge, and set his course to rebuild the Dark Tower and reconquer all the lost lands.
That was how the events in Overlord began.