The Necrons face off against the Eldar
The War in Heaven was a tumultuous conflict between waged by the C'tan and the Necrontyr against the Old Ones. The war caused incredible destruction throughout the Milky Way and the Immaterium.
History[]
War Begins[]
The Necrontyr Empire spread far across the Milky Way, but the Necrontyr had slow-moving space vessels and short lifespans. Dynasties within the empire began warring against each other, and vying for independence. To prevent the empire from falling apart, the Silent King Szarekh devised a plan to wage war against the immortal Old Ones. His plan successfully unified his people, and the War in Heaven began.
Though the Necrontyr had powerful technology in their own rights, they had no hope of succeeding against the Old Ones who had mastered powerful psionic abilities and had access to the Webway. The Necrontyr were pushed back, eventually contained almost entirely on their homeworld and posing little threat at all to the Old Ones. The Necrontyr began to fight amongst themselves once more.
The Tide Turns[]
The Triarch sought desperately for a way to reunite the Necrontyr -- and soon their prayers were answered when they encountered the C'tan. An alliance was formed, and necrodermis physical forms were constructed for the C'tan to inhabit. The C'tan brought immense power with them, with even more advanced starships and weapons. A C'tan called the Deceiver encouraged the Necrontyr to abandon their flesh and transfer themselves in necrodermis bodies of their own -- and thus, the Necrons were born.
Newly armed as such, the war against the Old Ones resumed. This time it was the Old Ones who were outmatched -- they attempted to retreat into the Immaterium, but even the Webway proved unsafe. The Necron were able to infiltrate the Warp through Dolmen Gates. The Old Ones grew desperate in the war.
With nowhere else to turn, the Old Ones psychically empowered a number of the races that they had created. Most notably, this included the Eldar. Using the power of the Warp, the psionic army struck back against the C'tan -- shattering the species. The C'tan were forced to seal off the Warp from the Prime Reality, an act which unintentionally shook all of subspace -- and the Realm of Chaos was reforged.
As creatures from subspace ferociously fought to enter the Prime Reality, the Old Ones worked to genetically create new races to fill their armies. These included the krork and the Jokaero -- but they were unable to protect the Webway from the dangers that filled it, and abandoned it as it became overrun by monsters like the Enslavers. It was because of this calamity that the Old Ones were eventually, at least, defeated.
War Ends[]
With the Old Ones defeated and the C'tan weakened, the Silent King made his move. The Necrons used their advanced weaponry to imprison the immortal C'tan. The cost of this rebellion was high, and as such once the C'tan had been eternally imprisoned, the Silent King commanded all of the Necrons to enter a state of stasis called the Great Sleep.
Source[]
The War in Heaven is derived from Warhammer 40k. For canon information visit the Warhammer 40,000 Wiki.