Undead History is a section of the Warcraft III: Reign of Chaos manual.
The Shaman, Ner'zhul: Origin of the Lich King
The orcish clans, bound by a noble, shamanistic culture for thousands of years on the world of Draenor, knew nothing of corruption or spiritual decay. But the sinister agents of the Burning Legion sought to forge them into a voracious, unstoppable army. The cunning demon, Kil'jaeden, second in command of the Legion, saw that the savage warriors had vast potential for murder and bloodshed – and set out to corrupt their tranquil society from within.
Kil'jaeden appeared to the orcs' most respected leader, the elder shaman Ner'zhul, and told him that he would bestow upon the orcs great power and make them the undisputed rulers of their world. He even offered the old shaman untold mystical knowledge if he agreed to bind himself and his people to the Legion's will. Calculating and power hungry by nature, Ner'zhul accepted Kil'jaeden’s offer and made a Blood Pact with the demon. By doing so, Ner'zhul had sealed the orcs' fate and damned them to become the unwitting slaves of the Burning Legion.
As time passed, Kil'jaeden recognized that Ner'zhul did not have the will or the brazen audacity to follow through with his plan of forging the orcs into a bloodthirsty horde. Ner'zhul, realizing that his pact with Kil'jaeden would only lead to his race's annihilation, refused to help the demon any further. Enraged by the shaman's defiance, Kil'jaeden swore to take vengeance upon Ner'zhul, and corrupt the orcs despite him. Kil'jaeden found a new, eager apprentice to lead the orcs on the path to oblivion - Ner'zhul's own nefarious protégé, Gul'dan.
With Kil'jaeden’s help, Gul'dan succeeded where his teacher had faltered. The evil, power-hungry Orc not only abolished the ancient practice of shamanism – which he replaced with the study of demonic Warlock magics – but united the Orc clans into the volatile Horde that Kil'jaeden had envisioned. Ner'zhul, powerless to stop his former apprentice, could only watch as Gul'dan masterfully transformed the orcs into mindless agents of destruction.
Years passed as Ner'zhul brooded silently upon the red world of Draenor. He watched as his people staged the first invasion of Azeroth. He heard the tales of the orcs' Second War against the Alliance of Lordaeron. He bore witness to the treachery and corruption that seemed to be destroying his people from within. Despite Gul'dan's masterminding the Horde's dark destiny, Ner'zhul knew that he himself was responsible for setting it all in motion.
Shortly after the end of the Second War, the news of the Horde's defeat reached the orcs who remained in Draenor. Ner'zhul, knowing that the Horde had failed its mission to conquer Azeroth, feared that Kil'jaeden and the Legion would take dire action against the remaining orcs. To escape Kil'jaeden's imminent wrath, Ner'zhul opened a number of mystical portals that lead to new, unspoiled worlds. The old shaman rallied the remaining orc clans and planned to lead them through one of the portals, and into a new directed destiny.
Before he could execute his plan, Ner'zhul was forced to deal with an Alliance expeditionary force sent to Draenor to destroy the orcs forever. Ner'zhul's loyal clans managed to hold the Alliance forces at bay while the old shaman opened the raging, magical portals. To his horror, Ner'zhul realized that the portals' tremendous energies were beginning to rip the very fabric of Draenor apart. As the Alliance forces pushed the orcs further back into the hellish world, Draenor began to buckle in on itself. Realizing that the battling clans would never reach the portals in time, Ner'zhul selfishly abandoned them and escaped with his elite followers in tow. The evil group of orcs crossed through their chosen portal just as Draenor blew apart in an apocalyptic explosion. The old shaman believed he'd been lucky to escape death... Ironically, he would live to regret his náiveté.
Kil'jaeden and the New Deal
Just as Ner'zhul and his followers entered the Twisting Nether – the ethereal plane that connects all of the worlds scattered throughout the Great Dark Beyond – they were ambushed by Kil'jaeden and his demonic minions. Kil'jaeden, who had sworn to take vengeance on Ner'zhul for his prideful defiance, tortured the old shaman mercilessly by slowly tearing his body apart piece by piece. Kil'jaeden kept the shaman's spirit alive and intact – leaving Ner'zhul painfully aware of his body’s gross dismemberment. Though Ner'zhul pleaded with the demon to release his spirit and grant him death, the demon grimly replied that the Blood Pact they had made long ago was still binding – and that he would make use of his wayward pawn once again.
The orcs' failure to conquer Azeroth as the Legion intended forced Kil'jaeden to create a new army to sew chaos throughout the kingdoms of the Alliance. This new army could not be allowed to fall prey to the same petty rivalries and infighting that had plagued the Horde. It would have to be dogged, merciless, and singleminded in its mission. This time, Kil'jaeden could not afford to fail.
Holding Ner'zhul's tortured, helpless spirit in stasis, Kil'jaeden gave him one last chance to serve the Legion or suffer eternal torment. Once again, Ner'zhul recklessly agreed to the demon's pact.
Ner'zhul's spirit was placed within a specially crafted block of diamond-hard ice gathered from the far reaches of the Twisting Nether. Encased within the frozen cask, Ner'zhul felt his consciousness expand ten thousandfold. Warped by the demon's chaotic powers, Ner'zhul became a spectral being of unfathomable power. At that moment, the Orc known as Ner'zhul was shattered forever, and the Lich King was born.
Ner'zhul's loyal Death Knights and warlock followers were also transformed by the demon's chaotic energies. The wicked spellcasters were ripped apart and remade as skeletal Liches. The demons had ensured that even in death, Ner'zhul's followers would serve him unquestioningly.
When the time was right, Kil'jaeden patiently explained the mission for which he had created the Lich King: Ner'zhul was to spread a plague of death and terror across Azeroth that would snuff out Human civilization forever. All those who died from the dreaded plague would arise as the Undead... and their spirits would be bound to Ner'zhul's iron will forever. Kil'jaeden promised that if Ner'zhul accomplished his dark mission of scouring humanity from the world, he would be freed from his curse and granted a new, healthy body to inhabit.
Though Ner'zhul was agreeable and seemingly anxious to play his part, Kil'jaeden remained skeptical of his pawn's loyalties. Keeping the Lich King bodiless and trapped within the crystal cask assured his good conduct for the short term, but the demon knew that he would need to keep a watchful eye on the Lich King. To this end, Kil'jaeden called upon his elite demon guard, the vampiric Dreadlords, to police Ner'zhul and ensure that he accomplished his dread task. Tichondrius, the most powerful and cunning of the Dread Lords, warmed to the challenge, fascinated by the plague's severity and the Lich King's unbridled potential for genocide.
Icecrown and the Frozen Throne
Kil'jaeden cast Ner'zhul's icy cask back into the world of Azeroth. The hardened crystal streaked across the night sky and smashed into the desolate, arctic continent of Northrend, burying itself in the deep, shadowed hallows of the Icecrown glacier. The frozen crystal, warped and scarred by its violent descent, came to resemble a throne, and Ner'zhul’s vengeful spirit stirred within it.
From the confines of the Frozen Throne, Ner'zhul began to reach out his vast consciousness and touch the minds of Northrend's native inhabitants. With surprising ease, he enslaved the minds of many indigenous creatures, such as ice trolls and the fierce wendigo - and drew their evil brethren into his growing shadow. He found that his psychic powers were almost limitless, and used them to create a small army that he housed within Icecrown's twisting labyrinths. As the Lich King mastered his growing powers under the Dread Lords' persistent vigil, he discovered a remote human settlement on the fringe of the vast Dragonblight. Ner'zhul decided to test his powers and his dread plague on the unsuspecting humans.
Ner'zhul sent the plague of undeath, which had originated from deep within the Frozen Throne, out into the arctic wasteland. Controlling the plague with his will alone, he drove it straight into the Human village. Within three days, every human soul in the settlement was dead. Yet, in a surprisingly short amount of time, the dead villagers began to rise as zombified corpses. Ner'zhul could feel their individual spirits and thoughts as if they were his own. The raging cacophony in his mind caused Ner’zhul to grow even more powerful – as if their spirits provided him with much needed nourishment. He found it was child's play to control the zombies' actions and steer them to whatever end he wished.
Over the following months, Ner'zhul continued to experiment with his plague of undeath by subjugating every Human inhabitant of Northrend. With his army of undead growing daily, he knew that the time for his true test was nearing.
For ten long years, Ner'zhul built up his power base in Northrend. A great citadel was erected above Icecrown and manned by growing legions of the undead. Yet, as the Lich King extended his influence over the land, a lone, shadowy empire stood against his power. The ancient, subterranean kingdom of Azjol-Nerub, which had been founded by a race of sinister humanoid spiders, sent their elite warrior-guard to attack Icecrown and end the Lich King's mad bid for dominance. Much to his frustration, Ner'zhul found that the evil Nerubians were immune to not only the plague, but to his telepathic domination as well.
The Nerubian spider lords commanded vast forces and had an underground network that stretched nearly half the breadth of Northrend. Their hit and run tactics on the Lich King's strongholds stymied his efforts to root them out time after time. Ultimately, Ner'zhul's war against the Nerubians was won by attrition. With the aid of the furious Dread Lords and his innumerable undead warriors, the Lich King invaded Azjol-Nerub and brought its subterranean temples crashing down upon the spider lords' heads.
Though the Nerubians were immune to his plague, Ner'zhul's growing necromantic powers allowed him to raise the spider warriors' corpses and bend them to his will. As a testament to their tenacity and fearlessness, Ner'zhul adopted the Nerubians' distinctive architectural style for his own fortresses and structures. Left to rule his kingdom unopposed, the Lich King began preparing for his true mission in the world. Reaching out into the Human lands with his vast consciousness, the Lich King called out to any dark soul that would listen...
Kel'Thuzad and the Cult of the Damned
There were a handful of powerful individuals, scattered across the world, who heard the Lich King’s mental summons. Most notable of them was the Archmage, Kel'Thuzad, of the magical nation of Dalaran. Kel’Thuzad, one of the senior members of the Kirin Tor – Dalaran’s ruling council – had been considered a maverick for years due to his insistence on studying the forbidden arts of necromancy. Driven to learn all he could of the magical world and its shadowy wonders, he was frustrated by what he saw as his peers’ outmoded and unimaginative precepts. Upon hearing the powerful summons from Northrend, the Archmage bent all of his considerable will to communing with the mysterious voice. Convinced that the Kirin Tor was too squeamish to seize the power and knowledge inherent in the dark arts, he vowed to learn what he could from the immensely powerful Lich King.
Forsaking his fortune and prestigious political standing, Kel’Thuzad abandoned the ways of the Kirin Tor and left Dalaran forever. Prodded by the Lich King’s persistent voice in his mind, he sold his vast holdings and stored away his fortunes. Travelling alone over many leagues of both land and sea, he finally reached the frozen shores of Northrend. Intent on reaching Icecrown and offering his services to the Lich King, the Archmage passed through the ravaged, war-torn ruins of Azjol-Nerub. Kel’Thuzad saw firsthand the scope and ferocity of Ner’zhul’s power. He began to believe that allying himself with the mysterious Lich King would not only be wise, but potentially fruitful.
After long months of trekking through the harsh arctic wastelands, Kel’Thuzad finally reached the dark glacier of Icecrown. He boldly approached Ner’zhul’s dark citadel and was shocked when the silent undead guardsmen let him pass as though he was expected. Kel’Thuzad descended deep into the cold earth and found his way down to the bottom of the glacier. There, in the endless cavern of ice and shadows, he prostrated himself before the Frozen Throne and offered his soul to the dark lord of the dead.
The Lich King was pleased with his latest conscript. He promised Kel'Thuzad immortality and great power in exchange for his loyalty and obedience. Kel'Thuzad, eager for dark knowledge and power, accepted his first great mission - to go into the world of men and found a new religion that would worship the Lich King as a god.
To help the Archmage accomplish his mission, Ner'zhul left Kel'Thuzad's humanity intact. The aged, yet still charismatic wizard was charged with using his powers of illusion and persuasion to lull the downtrodden, disenfranchised masses of Lordaeron into a confidence. Once he had their attention, he would offer them a new vision of what society could be - and a new figurehead to call their king...
Kel'Thuzad returned to Lordaeron in disguise, and over the span of three years, he used his fortune and intellect to gather a clandestine brotherhood of like-minded men and women. The brotherhood, which he called the Cult of the Damned, promised its acolytes social equality and eternal life on Azeroth in exchange for their service and obedience to Ner'zhul. As the months passed, Kel'Thuzad found many eager volunteers for his new cult amongst the tired, overburdened laborers of Lordaeron. Surprisingly, Kel'Thuzad's goal to pervert the citizens' faith in the Holy Light towards belief in in Ner'zhul's dark shadow was easily attained. As the Cult of the Damned grew in size and influence, Kel'Thuzad made sure to keep its workings secret from the authorities of Lordaeron at every turn.
The Forming of the Scourge
With Kel'Thuzad's success in Lordaeron, the Lich King made the final preparations for his assault against human civilization. Placing his plague energies into a number of portable artifacts called Plague Cauldrons, Ner'zhul ordered Kel'Thuzad to transport the cauldrons to Lordaeron where they would be hidden within various cult-controlled villages. The cauldrons, protected by the loyal cultists, would then act as plague generators, sending the plague seeping out across the unsuspecting farmlands and cities of northern Lordaeron.
The Lich King's plan worked perfectly. Many of Lordaeron's northern villages were contaminated almost immediately. Just as in Northrend, the citizens who contracted the plague died and arose as the Lich King's willing slaves. The cultists under Kel'Thuzad were eager to die and be raised again in their dark lord's service. They exulted in the prospect of immortality through undeath. As the plague spread, more and more feral zombies arose in the northlands. Kel'Thuzad looked upon the Lich King's growing army and named it the Scourge - for soon, it would march upon the gates of Lordaeron... and scour humanity from the face of the world.
An Heir Apparent
Though the Dread Lords were pleased that Ner'zhul's true mission had finally begun, the Lich King himself brooded within the tight, shadowy confines of the Frozen Throne. Despite his vast psychic powers and his complete dominion over the undead, he longed to be free of his icy prison. He knew that Kil'jaeden would never release him from his curse. And, due to his great power, he knew that the demons would destroy him as soon as his mission was completed.
Still, he had one chance for freedom - one chance to escape his terrible curse. If he could find a suitable host - some hapless dupe who was torn between darkness and light - he could possess that body and escape the confines of the Frozen Throne forever.
Thus, the Lich King sent his vast consciousness out once again and sought the perfect host...