Vault 117

Vault 117 is located in Petersburg, VA.

Experiment
The Vault 117 experiment was to test the effects of PTSD in an isolated environment for seven decades. The residents of Petersburg were told that Vault 117 could house all of them in the event of a nuclear war, while the soldiers were told that the vault was strictly a military zone, and any trespassers should be shot on sight.

Result
When the Great War occurred, hundreds of civilians from Petersburg fled to Vault 117 for safety. The soldiers stationed there were ordered by their commanders to turn them away. The civilians quickly began to riot, after which the soldiers were ordered to open fire, slaughtering dozens of civilians before they fled. The soldiers then retreated into the vault, where they were sealed for decades.

The population of the Vault remained steady for a few years, however in 2087, a wave of guilt-ridden suicide sharply declined the population from ~1,000 to only ~600. In 2092, the soldiers staged a revolt against their commanders who had taken position as Overseer, beginning a civil war inside the vault. At some point, the lower levels of the vault collapsed when a grenade was thrown into the armory, detonating the ammunition supplies inside.

In 2117, the door finally opened, and the majority of the remaining soldiers left the vault forever, wandering the wastes. A few remained, guarding the vault. Their descendants still guard the vault for reasons that they can't exactly place.