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The United Nations-Martian Congressional Republic Cold War (UN-MCR Cold War), usually referred to as the Cold War, was a state of political and military tension between the two superpowers of the Sol system, Earth (UN) and Mars (MCR). Tensions would eventually led to outright warfare after forces engaged on Ganymede, before the entire Sol System.


Vesta Blockade[]

Main article: Vesta Blockade

The Vesta Blockade was a significant confrontation between the UN and MCR during the Cold War at the asteroid station Vesta, during which the situation nearly escalated into war. While a standoff between UNN and MCRN ships escalated, with one MCRN cruiser singlehandedly disabling five UNN destroyers (the UNN Yasijuro being one of them)[1], a battle and subsequent war was avoided by diplomatic talks.[2]

However, the subsequent uneasy truce with the UN prompted the MCR to invest in and expand its military, diverting resources and personnel away from Mars' terraforming project and delaying its progress for more than 100 years.[3]

Anderson Station Massacre[]

Main article: Anderson Station Massacre (TV)

After Belter protesters seized control of Anderson Station the United Nations Marine Corps (UNMC) under Colonel Fred Johnson were sent to quell resistance. Colonel Johnson was not given information that the station had surrendered and ordered its destruction.[4] This event led to him becoming known as the "Butcher of Anderson Station", and aggressively cooled relations with the Belt and Mars.

Callisto Insurrection[]

Main article: Callisto Insurrection

The Callisto insurrection was an event involving high tensions amongst the inhabitants of Callisto and between factions backed by either the UN and MCR as a proxy conflict. The crisis was notable for causing the death of Charanpal Avasarala, the son of United Nations Secretary-General Chrisjen Avasarala. His commander Cotyar Ghazi blamed himself for the death of Charanpal. While the result of the conflict is unknown, the UN and MCR both established facilities on Callisto and claimed it as their respective protectorate.

Operation Silent Wall[]

Main article: Operation Silent Wall

Operation Silent Wall was an anti-pirate campaign led by the MCRN and MCRN Jupiter fleet flagship the Donnager with four Morrigan-class patrol destroyers, the MCRN Damascus, Iceni, Avalanche and Hamill-Stewart, and two Corvette-class light frigates, the MCRN McCabe and Valenza. The operation was extended over years and ultimately proved to be successful, largely reducing pirate activity in the Belt against MCR vessels.

Discovery on Phoebe[]

Main article: Discovery on Phoebe

The MCR and Protogen, an Earth-based contracted company, discover a mysterious alien substance on Phoebe, later named the Protomolecule. Protogen members then killed the MCR scientists and officials on Phoebe to hide their discovery, smuggling a sample of the Protomolecule off the station with the Osiris. Later, the MCRN Donnager is sent to investigate but finds that the station has had a flash-fire and left no survivors.[5]

Demise of the Scopuli and Canterbury[]

Main article: Demise of the Scopuli and Canterbury

Hired by a faction of the Outer Planets Alliance (OPA) under Anderson Dawes, the Scopuli intercepts a ship belonging to Protogen that it believes to be a freighter carrying the Protomolecule, or of importance as suspected by Julie Mao, daughter of Protogen's CEO Jules-Pierre Mao responsible for the cover-up and voluntary member of the OPA. However upon getting close the intercepted freighter turns out to be the Anubis, an Amun-Ra-class stealth frigate and boards the Scopuli taking the crew prisoner and leaving the ship abandoned as part of a ploy.[6]

After receiving a distress call the ice hauler vessel Canterbury of the Pur'n'Kleen Water Company moves to meet the freighter. Upon getting close a boarding team led by Jim Holden boards via the Canterbury's shuttle, the Knight. The distress beacon is then discovered to have been planted and the ship abandoned. At this point, a mysterious ship, the Anubis which attacked the Scopuli earlier on, appears and nukes the Canterbury, destroying the ice freighter.[7]

The incident was noted and subsequently investigated by the MCRN Donnager, and the surviving crew of the Canterbury on the Knight presumed the attack to have been instigated by the MCR due to the Anubis' advanced stealth technology. Before the Donnager was able to intercept any messages sent by the Knight, Holden broadcasted a message claiming the MCR destroyed the Scopuli and Canterbury.[8] This led to revolts on Ceres and other stations against the Belt, which already suffered from reduced water supply. Captain Yao of the Donnager then tried to persuade Holden of renouncing that claim because it was incorrect.[9]

Attack on the Donnager[]

Main article: Attack on the Donnager (TV)

The MCRN Donnager firing its PDCs against the Protogen stealth ships.

The attack on the Donnager happened after the flagship picked up civilian survivors from the shuttle Knight. The Donnager came under attack from 6 unidentified stealth ships belonging to the Amun-Ra-class of Protogen, trying to frame the situation as to provoke conflict between the UN and MCR. While the Donnager was able to defend itself and destroyed 4 ships, it was finally boarded and as to avoid the ship being taken, Yao ordered Condition Zero, self-destructing the Donnager. The crew of the Knight was evacuated onboard the MCRN Tachi with MCRN Lieutenant Lopez, and fled the ship before it was destroyed.[10]

The MCR did not receive any information regarding the circumstances of the Donnager's destruction, and tensions with the UN rose dramatically. While Fred Johnson used Tycho Station's sensors to ascertain himself what happened, the UN tried to dispatch the UNN Orinoco to investigate the happenings, but arrived too late at the scene.[11] Johnson, using data collected by the Donnager during the battle, revealed to the public that the drive signatures matched those built at Bush naval shipyards, a UN military shipyard facility.

Avasarala tried to investigate whether the MCR or a rogue MCR faction was responsible for the incidents, by using the UN ambassador to Mars, Franklin DeGraaf to cause concern in the Martian government and listen to their backchannel communication about if stealth composites had been stolen. Since Mars seemed concerned about the location of them, she concluded that Mars is not responsible for building the stealth ships. However, DeGraaf was expelled for life from Mars for this intelligence issue, and diplomatic relations ceased.[12]

Infection of Eros Station[]

Having found the samples of the Protomolecule in the body of Julie Mao, Protogen under lead scientist Antony Dresden was able to use it to infect the population of Eros Station, a joint UN-MCR protectorate, as an controlled experiment to study.[13] Under the guise of a ship detonating at the docks, Eros was quarantined and the UN and MCR led to believe a toxic spill had happened. A naval blockade was then imposed by both nations. [14]

Destruction of Phoebe[]

Main article: Destruction of Phoebe

UN Security Council is informed of the destruction of Phoebe by the MCRN Scirocco.

When the UNN Nathan Hale was nearing Phoebe to uncover MCR secrets they believed were on the station in connection to the recent incidents, the MCRN Scirocco fired on the station, destroying it to prevent the Nathan Hale from boarding the station and uncovering secrets unknown to the Scirocco itself. The debris of Phoebe slowly disintegrated and fell into Saturn.[15]

Destruction of Deimos[]

Main article: Destruction of Deimos

News feed of Deimos being destroyed by the UN

In response to the MCR destroying Phoebe Station, the UN resorted to attack and destroy Deimos, a moon of Mars and military facility, as equal answer to the attack.[16] The civilian population of Mars was furious about the attack and resentment towards the UN grew massively.

Eros incident[]

Main article: Eros incident (TV)

Rocinante tactical screen of Eros approaching the inner Solar System.

The Eros incident was an event that caused the death of the entire population of Eros Station, numbering 1.5 million inhabitants. The station was deliberately infected with Protomolecule which took over unintentionally and eventually caused Eros to move through space sunwards, after an attempt by the Tycho Station OPA had been made to destroy Eros with the LDSS Nauvoo. The new course of Eros led the UN to believe it was headed for Earth, and suspicions of a new Martian weapon rose. Earth answered with launching half its nuclear arsenal to destroy Eros, and notified the MCR that this is not a pre-emptive strike on Mars. Eros was able to evade the nuclear warheads however, but inexplicably it changed course away from Earth and continued to fly sunward, until crashing into Venus.[17]

Ganymede incident[]

Main article: Ganymede incident (TV)

UNN and MCRN ships firing on one another in orbit above Ganymede Station.

On Ganymede, Protogen tested and unleashed a specimen of Project Caliban as a weapon developed from Protomolecule. Initially released in the UN sector of the moon's stations, it killed multiple UNMC (United Nations Marine Corps) and MMC (Martian Marine Corps) soldiers while being filmed by a drone as a demonstration of Caliban's prowess. Due to the high tension between Earth and Mars, and the intentional jamming of communication between the UN and MCR ships and their marines, hostilities quickly broke out above Ganymede. UNN and MCRN ships engaged to fire on one another, and the PDC (Point Defence Cannon) fire in orbit damaged and destroyed the mirror stations providing the agricultural domes with sunlight, crashing onto the surface and severely damaging Ganymede Station.[18]

Ganymede remained under the occupation of the MCRN from orbit, imposing flight restrictions and requiring authorization for landing access.[19] The subsequent ecological and societal collapse of Ganymede Station was a humanitarian catastrophe and led to a refugee crisis and subsequent famine across the outer planets.[20]

UN-MCR peace summit[]

Quickly after the situation had been assessed, fighting ended with an unstable truce, and a peace summit in New York City had been hastily organized to calm the tension.[21] The lone survivor of the ground battle, MCRN Gunnery Sergeant Roberta Draper, was summoned to present what she saw on the surface to both the MCR delegation and UN government representation. The delegation claimed MCRN Private Richard Travis fired first out of nervosity, igniting the battle in orbit in a chain reaction.[22] However, Draper was privately pressured by Captain Martens to withhold her witnessing Project Caliban and later learned that Martens himself knew what the project was, seeking asylum on Earth in desperation.[23] The peace summit concluded with Mars providing for most of the rebuilding costs, but keeping Ganymede temporarily under MCR control.

In reality, the peace summit only served to safeguard and transport Caliban off Ganymede in time, a plan covertly brokered between Jules-Pierre Mao and MCR defence minister Pyotr Korshunov. The occupation of the MCRN served to cover-up the delivery of Project Caliban to a covert faction of the MCR which dispatched the black ops MCRN Karakum to pick up the specimen.[24]

Karakum incident and Battle of Ganymede[]

Secretary-General Sorrento-Gillis and Undersecretary Errinwright discussing a declaration of war with the battle of Ganymede.

However, the Karakum would be shot down by UN forces acting on the orders of United Nations Undersecretary Sadavir Errinwright before it could reach its destination, while Korshunov was simultaneously assassinated by him to ensure that the only ones who would be able to secure the Protomolecule as a weapon would be the UN. Errinwright also attempted to kill Avasarala covertly meeting with Jules-Pierre Mao on the Guanshiyin to resolve the situation with the Protomolecule, framing her as if she were to conspire with him as part of a conspiracy, when in reality it was him conspiring and then falling out with Mao. He now had free reign to control the UN behind Sorrento-Gillis and trigger a war as what he saw as a pre-emptive strike against Martian aggression.[25]

Quickly thereafter, fighting broke out again between UNN and MCRN ships at Ganymede, and Errinwright manipulated acting Secretary-General Esteban Sorrento-Gillis to finally declare war on the MCR after heightened tensions escalating.[26] However, this lead to the UN-MCR War, resulting in millions of civilian casualties, billions of dollars worth lost to damaged infrastructure, the destruction of dozens of military vessels, the resignation of Sorrento-Gillis, the arrest of Sadavir Errinwright, and the ultimate rise of power for Chrisjen Avasarala in the UN.


  1. The Expanse TV series - Season 3, Episode 5: "Triple Point"
  2. The Expanse TV series - Season 2, Episode 1: "Safe"
  3. The Expanse TV series - Season 2, Episode 1: "Safe"
  4. The Expanse TV series - Season 1, Episode 5: "Back to the Butcher"
  5. The Expanse TV series - Season 1, Episode 4: "CQB"
  6. The Expanse TV series - Season 1, Episode 9: "Critical Mass"
  7. The Expanse TV series - Season 1, Episode 1: "Dulcinea"
  8. The Expanse TV series - Season 1, Episode 2: "The Big Empty"
  9. The Expanse TV series - Season 1, Episode 3: "Remember the Cant"
  10. The Expanse TV series - Season 1, Episode 4: "CQB"
  11. The Expanse TV series - Season 1, Episode 5: "Back to the Butcher"
  12. The Expanse TV series - Season 1, Episode 6: "Rock Bottom"
  13. The Expanse TV series - Season 1, Episode 10: "Leviathan Wakes"
  14. The Expanse TV series - Season 2, Episode 4: "Godspeed"
  15. The Expanse TV series - Season 2, Episode 1: "Safe"
  16. The Expanse TV series - Season 2, Episode 2: "Doors & Corners"
  17. The Expanse TV series - Season 2, Episode 5: "Home"
  18. The Expanse TV series - Season 2, Episode 6: "Paradigm Shift"
  19. The Expanse TV series - Season 2, Episode 9: "The Weeping Somnambulist"
  20. The Expanse TV series - Season 2, Episode 10: "Cascade"
  21. The Expanse TV series - Season 2, Episode 7: "The Seventh Man"
  22. The Expanse TV series - Season 2, Episode 9: "The Weeping Somnambulist"
  23. The Expanse TV series - Season 2, Episode 11: "Here There Be Dragons"
  24. The Expanse TV series - Season 2, Episode 13: "Caliban's War"
  25. The Expanse TV series - Season 2, Episode 13: "Caliban's War"
  26. The Expanse TV series - Season 3, Episode 1: "Fight or Flight"