The 100 Codexery

The Great War

One exchange of fire, and the sky became the only safe address left on Earth.

The Great War is the apocalyptic nuclear conflict that, in the world of The 100, rendered Earth's surface toxic and forced the entirety of remaining humanity into orbital exile aboard the Ark, a massive space station. It is the foundational catastrophe of the series—the event that created the two-tiered society of space-dwellers and the feral surface populations known as the Grounders, and whose true causes and consequences drive the central mystery of the show.

Rather than being a simple historical footnote, the Great War functions as a living, contested narrative. Characters on the Ark inherit a sanitized, almost mythic version of what happened, while the Grounders carry fragmented oral traditions that paint a very different picture. As the series unfolds, each new revelation about the war's origins—whose hands held the triggers, what was truly at stake, and who was deliberately left behind—reshapes alliances, identities, and the moral calculus of whether humanity deserves to reclaim its home world.

Quick Facts

Type
Global nuclear conflict
Consequence
Earth's surface rendered radioactive and largely uninhabitable
Primary survivors
Humanity in orbit aboard the Ark space station
Surface descendants
The Grounders (various tribal factions)
Timeframe
Roughly 75–100 years before the series begins
Narrative role
Central mystery and moral engine of the entire series

Lore & Background

In the sanitized histories taught to children on the Ark, the Great War is presented as a sudden, almost unavoidable catastrophe: a cascade of nuclear strikes that turned the atmosphere into a lethal cloud and boiled the oceans into irradiated sludge. The official narrative emphasizes collective human failure—greed, miscommunication, a chain of political blunders that spiraled beyond any single nation's control. In this telling, the Ark was humanity's last desperate ark (no pun intended), a lifeboat launched in the war's final hours that carried the last viable population into the void.

The Grounders, however, tell a different story passed down through generations of scarred survivors. Their oral traditions speak of a war that was not so much a mutual annihilation as a targeted extermination—that the surface was not merely collateral damage but a deliberate sacrifice, that the people who built the Ark chose who would live in the sky and who would be left to choke on the fallout. These accounts are fragmented, mythologized, and often contradictory between tribes, but they share a common thread: the war was not an accident. Someone decided.

The series slowly peels back the official narrative, revealing that the war's roots entangle weapons industries, resource scarcity, and a small group of individuals who attempted to prevent the exchange and were instead scapegoated or erased from the record. The truth is never a single clean revelation but a mosaic of half-truths, suppressed documents, and lived trauma, forcing characters to reckon with the possibility that the society they call civilization was built on a lie of convenient omission.

Reader's Guide

RECOVERED FRAGMENT — Ark Historical Archive, Restricted Shelf 7

The Great War is the event around which all subsequent human history is organized. On the Ark, it is taught as a singular catastrophe: a global nuclear exchange that poisoned the atmosphere and made the surface lethal. Children learn the date, the approximate number of nations involved, and the moral lesson that hubris destroyed the world. It is, in the official curriculum, a closed chapter.

Among the Grounders, the war is not a chapter but a scar. Tribal oral traditions vary widely. Some factions speak of a 'sky-fire' sent by the gods as punishment for humanity's hunger. Others describe a 'chosen flight,' in which a privileged few ascended to the metal sky while the rest were abandoned to the burning ground. These accounts are not recorded in any written form; they are sung, scarred, and performed. They are, by the Grounders' own reckoning, the only true history.

As the series progresses, the 'official' narrative fractures. Characters discover that the war's causes were far more deliberate than the Ark's textbooks suggest, that certain individuals and institutions bore specific, culpable responsibility, and that the decision to leave the surface behind was not purely a survival imperative but a political act with winners and losers. The shift in understanding is not a single dramatic reveal but a slow, painful accumulation of evidence that forces each faction to re-examine who they are and who they owe a debt.

FAN NOTE: Much of the 'true' history remains deliberately ambiguous in the show. Specific names, exact trigger events, and the full chain of causation are hinted at but never fully documented on-screen. Any fan theory that pins the war to a single named antagonist or a single specific date should be treated as speculation, not canon.

Did You Know?

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