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Mariposa Military Base

map marker: Military Base
leaders: Lieutenant (Fallout)

Melchior (Fallout 2)

factions: Supermutants
quests: Destroy the source of the Mutants

Mariposa Military Base was a top-secret United States military facility built to house Forced Evolutionary Virus research previously conducted at West Tek, located somewhere in the area of the Mariposa unincorporated community in California. The name Mariposa means "butterfly" in Spanish.




Pre-war history

The construction of Mariposa started in October 2076 when large progress was made in FEV research, and the government preferred to move the project to a location under military supervision. On January 7, 2077, Major Barnett ordered transfer of all FEV research to the newly-constructed Mariposa Base, despite objections by the research team. Along with the scientists, a military team commanded by colonel Robert Spindel, which previously monitored the experiments at West Tek was sent to Mariposa. Spindel's second-in-command was captain Roger Maxson. The FEV project was moved to Mariposa and tested on human subjects. The vats were giant tanks filled with liquid FEV. As part of the research project, human subjects were dipped inside them and then examined to learn how to control and harness the process. The experiments on humans were kept secret even from Spindel and his soldiers.

Wartime events

On October 10, Maxson and his men were horrified to discover that the scientists at Mariposa were using military prisoners as test subjects in their experiments with the Forced Evolutionary Virus. Morale in the base broke down, and Spindel suffered a mental breakdown, eventually committing suicide 5 days later. Maxson's men turned to him for leadership.

After interrogating Robert Anderson, the chief scientist, and learning about the extent of their actions, Maxson executed him, and the other scientists soon followed. Maxson, now in control of the entire base, declared himself to be in full desertion from the army via radio on October 20. Strangely, he got no response, as the rest of the army was busy fighting the Chinese threat. Three days later, the bombs were launched, and the Great War ended two hours after it started.

The Mariposa Military Base survived, the soldiers within protected from the radiation and FEV flooding the wasteland. Two days later at Mariposa, a scout in Power Armor (Platner) was sent out to get specific readings on the atmosphere. He reported no significant radiation in the area surrounding the facility. After burying the scientists in the wastes outside of Mariposa, the soldiers sealed the military base, then headed out into the desert, taking supplies and weapon schematics with them. Captain Maxson led his men and families to the government bunker at Lost Hills, eventually forming the Brotherhood of Steel.

The base was left sealed, but over the years, it slowly fell into disrepair, and eventually various creatures made their way inside, mutating due to FEV exposure and infesting the surrounding area, attacking fledgling human settlements and caravans. The problem was becoming increasingly severe, to the point when Harold, a caravan master from the Hub, mounted an expedition in 2102 to locate and destroy the source of mutants.

Master's Army

FEV vats at Mariposa

Dr. Richard Grey was one of the explorers who was part of the expedition. Harold led the men into Mariposa, but failed to account for the automated defenses, which were still online, and promptly attacked the explorers. Taking heavy casualties, they made their way to the deepest, fourth level, the F.E.V Vats, where a crane smashed into the two surviving explorers, Harold and Richard Grey. The former was knocked out, the latter landed in one of the virus vats, succumbing to a severe overdose.

In pain, horribly mutated, he crawled into the control room, as his intellect grew. In a few days, he was neurolinked to the base computer, drawing upon its sizeable databanks. As he created the idea of the Unity, wanderers began to enter the facility, and Grey patiently captured and dipped them, in order to create beings as perfect as him. When the first true supermutants were created, he set out to create a true mutant army, at the same time deciding to look for a permanent base of operations. In 2155, one of his patrols located a group of vault dwellers from the LA Vault, and he made the decision to transfer himself there, occupying the Vault.

The base was entrusted to the Lieutenant, one of the greatest supermutant minds to exist. Mariposa was rebuilt and cleaned up, once again becoming the magnificent military base it was before the war. Supermutants roamed the halls, restocking the armories and medical base and soon it became the staging area for their assault on humanity, as well as the only supermutant production center.

Then came the Vault Dweller in 2162. It is unknown whether or not he infiltrated the base or blasted his way in - suffice to say, once he was through, Mariposa was little more than a caved-in, smoldering ruin.

Enclave's excavations

Main article: Example of field operation - Mariposa Military Base excavation

In 2236, the Enclave discovered the remnants of the Mariposa Base. Soon, assault squads combed the desert for slaves they could use to mine the military base and get to the vats. One of the squads included soldier Frank Horrigan. Enclave construction crews, as well as human and super mutant slaves began excavations. In September they uncovered FEV, and mutations began to occur in the human workers. Frank Horrigan comes into contact with the virus and is sent to the Enclave labs for study.

In 2237, having obtained the FEV data, the Enclave abandoned the site after more mutations occurred, causing 2nd Generation super mutants to arise. The Enclave left a single squad behind to wipe out the super mutants, but the mutants, using armaments they had cached in the base during excavation, reduced the squad to ashes after suffering heavy casualties. The remaining 1st and 2nd Generation super mutant slaves decided to remain in the Base, and the group formed a new community under the leadership of Melchior, whose magic talents had allowed them to hide the weapons.



Square footage: 30000 ft

The Mariposa was a reinforced military base, constructed in the middle of nowhere, in the side of a mountain. The exterior had a characteristic white lining and massive air conditioning vent providing fresh air for the complex. Inside, it consisted of four levels, stretching across a mile of depth.

Fallout 2

To get in the base you will need to find the long metal pole and put it on the rail cart. Next you put some dynamite on the rail cart and push it down.

Stronghold Level 1

Square footage: 40000 ft

The first level of Mariposa housed the gear needed for any excursions, as well as a staging area for patrols. Oddly, the main control computers for the base's forcefields and robotic guardians were located here, allowing any infiltrator to considerably sabotage the base, just by altering the Pest Control setting for the robobrains, in addition to altering the forcefield status remotely. Apart from that, guard barracks were located on this level, for off-duty surface security teams.

Fallout 2

Stronghold Level 2

Square footage: 60000 ft

The primary soldier living quarters, medbay and armory were located on this level. The quarters were spacious, although spartan in design, with a large stockpile of weapons just around the corner and a well equipped sickbay, stocked chock full of medical chems, surgical equipment and medical beds with integrated life support systems.

Fallout 2

Stronghold Level 3

Square footage: 80000 ft

The third level was divided in two, one was the general access area, where the assembly room and elevator to the commander's office were located, the second a military prison with an elevator going directly to the Vats. When Mariposa was operating under government jurisdiction, experimenting with FEV, only scientists and their security staff were allowed into the prison area and the Vats - soldiers under colonel Spindel and Roger Maxson were (rightly so) barred from entry.

Fallout 2


Square footage: 60000 ft

Divided in two as well, the deepest level housed the massive FEV Vats, together with their control room, scientist living quarters as well as the base commander's office. As with the third level, access to the FEV research area was strictly limited, with only scientists being allowed to enter. A special contaiment squad, the supermutant Vat Team 9, was stationed in the room near the cell block access elevator, to deal wth any potential disturbances. It was composed of three soldiers.

The Vats control room was where the base's mainframe was also located, holding personnel logs (Boyarsky, Roger Maxson, Richard Grey etc.) as well as the self-destruction initiation subsystem. Encrypted behind a firewall, these were nonetheless accessible for a skilled hacker. Alternatively, just blowing the console up would trigger the self destruct sequence, but the base would be set to alert status, powering up the forcefields.

Mariposa Encryption Codes

17652-1028-1285362 - 1 minute silent self destruct sequence
67209-5574-7805564 - 30 second self destruct, set base to alert
55658-8678-1251533 - set base to alert status
31914-1041-1251514 - 3 minute silent self destruct sequence
53478-2565-7763929 - 3 minute self destruct sequence, set base to alert

Fallout 2

Appearances in games

The Mariposa Military Base appears in Fallout and Fallout 2. It is mentioned in Fallout 3 by Harold in Oasis. The base is also mentioned in a terminal located in Vault 87.

Behind the scenes

According to Chris Taylor, Mariposa Military Base is based on Fort Ord. That's an old military base that has been shut down near Monterey Bay. It was called Base Omega in early design documents.

Related Holodisks


Fallout 2

Mariposa Military Base
Locations in Fallout
Locations in Fallout 2

This article uses material from the "Mariposa Military Base" article on the Fallout wiki at Wikia and is licensed under the Creative Commons Attribution-Share Alike License.


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