Euclid 3151.svg
System Information
X:Y Coordinates349.466 : -70.614[e]
Spectral classK3V[1]
Recharge time194 hours[1]
Recharge station(s)None[1]

The Euclid system contains at least one habitable planet, Euclid II, and as of 3151 was located in the New Avalon Prefecture of the New Samarkand Military District within the Draconis Combine.[2]

System Description[edit]

The Euclid system is located near the Leamington and Plymouth systems[3][4] and consists of a class K3V primary orbited by at least two planets.[1]

System History[edit]

The Euclid system was settled in 2632 by the Federated Suns.[1]

Political Affiliation[edit]

Euclid II[edit]

Euclid II
Euclid Orbital View.jpg
System position2nd[1]
Jump Point distance4.62 days[1]
Moons2 (Autolycus, Theon)[1]
Surface gravity0.85[1]
Atmospheric pressureStandard (Tainted)[1]
Equatorial temperature34°C (High)[1]
Surface water53%[1]
Highest native lifeFish[1]
History and Culture
PopulationCa. 50,000,000 (2750)[1]
9,000,000 (3035)[1]
19,112,300 (3075)[1]
Government and Infrastructure
Noble RulerCount of Euclid
HPG ClassB[1]

Euclid II - more commonly known simply as Euclid - is the second planet in the system and has two moons named Autolycus and Theon.[1]

Planetary History[edit]

Early History[edit]

The planet that would become known as Euclid was initially discovered by scientific observers on Terra in the late twenty-second century using astronomical observations, and it was one of the worlds identified for exploration when the technology became available. The K3V star in the Euclid system was what attracted initial studies of the system, with Euclid's oxygen-nitrogen atmosphere showing up in subsequent spectrographic data. A scout was dispatched to the system in 2215, but discovered disappointing results. At first glance, Euclid seemed a very favorable prospect for colonization; although the planet had less water than Terra, it still had a decent quantity of salt-water oceans and more water in total than many other worlds, as well as an atmosphere that was both at a survivable pressure and temperature. The native life and ecology of Euclid was inimical to human life, however; all of the native life, both plant and animal, was determined to be based on what were essentially giant acellular macromolecules. Unlike their closest comparators on Earth, prions and viruses, the native life on Euclid had advanced structures - photosynthetic, respiratory, digestive and nervous systems - and simply didn't use DNA. The native life was pervasive and unintentionally hostile to human life; while some of the lifeforms would try feeding on terrestrial life - something that was toxic to the native life - the native life forms caused unintentional poisoning in Terran life, along with immunological or allergic reactions that could be lethal.[1]

With the planet marked as unsuitable for colonization, the system was ultimately named Euclid as a reference to the bizarre geometric forms that the native life tended to form, ranging from simple Euclidean structures to exotic hyperbolic geometries. Euclid would be visited over the following centuries by teams either performing scientific research or exploiting the biochemical potential of the planetary life, humans who attempted to breathe the atmosphere would often end up displaying symptoms akin to asthma in a matter of minutes.[1]

The Star League[edit]

Euclid was finally colonized in 2632, a colonization made possible by the technological advances of the Star League era. The colonization efforts were led by an industrial consortium looking to exploit the planetary ecosystem, although the consortium also generated revenue through tourism, with a resort being founded to allow people to visit and view the exotic, colorful geometries of the native life, and over time land was sold to the rich for summer homes and then to industrial workers who were visiting the planet on long-term industrial contracts. The planetary economy thrived during the twenty-eighth century as a result of careful reinvestment of the profits made from tourism and industry, with additional settlers arriving in waves. The population peaked at more than fifty million people prior to the collapse of the Star League.[1]

Succession Wars[edit]

The First Succession War was hugely damaging to Euclid, despite the world never being attacked; the population of Euclid were highly dependent on imported technology and food, and the industries on the planet were too specialized to compensate for loss of off-world resources that the First Succession War inflicted on the planet. A significant part of the population of Euclid abandoned the planet for other nearby, more hospitable worlds, while those who remained on the planet continued to try and support themselves and the remaining technology using spare parts, salvage and effort. Essential infrastructure like power plants and filters managed to struggle on through the First Succession War, but the Second Succession War proved to be too much; the most talented engineers and scientists had abandoned the planet, and the high technologies needed could no longer be manufactured or supported.[1]

The population of Euclid had already been experimenting as best they could with lower-technology local substitutes like sealed greenhouses and combustion engines as well as inefficient water distillers, and through brute force and herculean effort the population managed to survive both the Second and Third Succession Wars but paid a heavy price for it. Environmental contaminants caused a range of birth defects and unusual diseases, and the population would continue to decline at approximately one percent a year until 3035, when it reached a nadir of just nine million people.[1]

Also working against the overall population was the tyrannical nature of the planetary nobility - sometimes described as a "highly authoritarian oligarchy". Power had been concentrated in the hands of the nobility because the efficiencies possible by scale ensured that the largest operations on the planet were the most profitable, and essential industries came under control of the nobility. Through their grasp over those industries on the planet that were essential to life, the nobility held the power of life and death over their subjects. They also controlled the still-profitable biochemical industries, which were in turn responsible for providing the inoculations needed to protect the peasantry from the natural contaminants they could be exposed to.[1]

With the implicit endorsement of the local ComStar representatives the nobility moved to ensure that critical knowledge was concentrated into specific "guilds" owned by the nobility; these guilds controlled such areas of technology as agronomy and water treatment, making it difficult for any of the lower orders to generate new farming and water treatment operations. While the upper classes retained a higher standard of living, life on Euclid for the peasantry resembled that of a typical Skid Row planet by the year 3000.[1]


In 3010 Count Marian Fessul came to power, marking a breaking point for the population. While the Federated Suns government was aware of the abuse of power by the planetary nobility, the Federated Suns government was unable to intervene with planetary governance. Fessul was the product of a twisted family environment that shaped him into a clinical sadist and psychopath who would later be referred to as a pocket Claudius Steiner. His abuses of power went beyond anything that the population had experienced before, and whereas both First Princes Andrew Davion and Ian Davion had overlooked past abuses because of larger issues, Hanse Davion acted after ascending to the throne.[1]

While Hanse couldn't intervene directly, he used the wealth of the Davion family in concert with several other family members to buy out the biochemical industries on Euclid, thereby removing the source of the nobility's power. Hanse then appointed a new Count to the planet, John Zibler, and dispatched him with a team of managerial and social specialists tasked with reversing Euclid's three-century decline.[1]

The planetary nobles on Euclid were intertwined with the government, giving Zibler a free hand in making replacements as he saw fit. He held back from eviscerating the government wholesale and instead persuaded many to remain in their posts through incentives such as shares in planetary industries or offers of passage offworld to make the decades-long transition in government and planetary reforms that were needed. Zibler implemented reforms that included a range of educational programs teaching useful trades, jump-starting a wide range of low-tech industries. He enacted public works that improved the seals and filters on homes, farms and water systems as well as eliminating price-gouging. This led to many families being able to afford to send members to school, while the various public works resulted in the next generation of the population being the healthiest born in a century and a half.[1]

The release of information from the Helm Memory Core twenty years after Hanse's intervention saw another increase in prosperity and health for the population; the technologies made possible included items that made farming and filtration on Euclid less expensive - although still challenging - as well as providing detailed biochemical technologies that helped protect children from the contaminants endemic to Euclid. This resulted in the population beginning to climb in 3035, and by 3075 the total population had doubled.[1]

In 3075 the planetary population was concentrated in seven major cities, the inhabitants of which made up nineteen out of every twenty people. It was easier to reduce the cost of living on Euclid by concentrating the population in cities and thereby taking advantage of economies of scale, and all seven cities were located in some of the most favorable climes to be found on one or other of the two planetary supercontinents, Proclus and Pappus. Each city was located on an ocean shore or close to a river that could be easily navigated. Buildings were all sealed, and were generally overpressurized compared to the local atmosphere, and the streets were covered in either transparent glass or polymer tents. This form of construction was easier to expand than domed cities, and the various open areas of the city were provided with filtered air. There were relatively few roads on the planet, and those roads that did exist were generally short and led to important industrial sites or mining facilities. Personal cars were rare, with most transport being either by electrified trolley or light rail within cities or via airship or oceangoing vessels for longer journeys. Local industries were meeting basic needs by this point, although many were dependent on supplies of advanced materials or tooling from offworld.[1]

Euclid's two co-orbital moons were named Autolycus and Theon and shared virtually the same orbit, but never approached closer than 2,500 km to each other. The interaction between the two moons resulted in periodic exchanges of momentum that would elevate one moon's orbit by fifty kilometers while dropping the orbit of the other by a corresponding amount, effectively causing the two to swap orbits.[1]

Military Deployment[edit]



Euclid has two supercontinents named Pappus and Proclus.[1]

Planetary Locations[edit]

  • Pythagoras: a city.[37]

Companies and Industries[edit]

Map Gallery[edit]

Nearby Systems[edit]

Closest 36 systems (34 within 60 light-years)
Distance in light years, closest systems first:
Plymouth 5.7 Leamington 20.8 Parma 21.1 Willowick 21.5
Unkador 21.6 Bellevue 25.0 Sturganos 32.7 Korvitz 32.8
Gambier 34.0 Huron 34.4 Delphos 35.1 Quincy 36.8
O'Fallon 38.1 Ramona 38.2 Saltville 40.5 Petrolia 41.4
Capac 41.8 Maison 45.4 Meinrad 45.5 Mansfield 45.9
Sylvester 46.1 Keytesville 47.3 Peabody 50.7 Macomb 51.0
Newton 51.3 Declan 52.0 Leipsic 53.3 Paulding 53.9
Saginaw 55.8 Andalusia 56.9 Lynchburg 58.2 Lexington 58.6
Imbrial 59.2 Monroe 59.7 Point Barrow 60.7 Cahokia 60.8


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.30 1.31 1.32 A Time of War: Companion, p. 150: "Euclid"
  2. 2.0 2.1 Shattered Fortress, p. 103
  3. 3.0 3.1 Era Report: 3145, p. 39: "Inner Sphere - [3145] Map"
  4. 4.0 4.1 Field Manual: 3145, p. VI: "Inner Sphere - [3145] Map"
  5. Handbook: House Davion, p. 18: "Federated Suns at their Founding - [2317] Map"
  6. Handbook: House Davion, p. 48: "Federated Suns after Age of War - [2571] Map"
  7. Historical: Reunification War, p. 159: "Inner Sphere - [2596] Map"
  8. Era Report: 2750, p. 37: "Inner Sphere - [2750] Map"
  9. Field Manual: SLDF, p. xi: "Inner Sphere - [2764] Map"
  10. Historical: Liberation of Terra Volume 1, p. 11: "Inner Sphere - [2765] Map"
  11. Field Report 2765: AFFS, p. 29: "Federated Suns Armed Forces Deployment Map - [2765]"
  12. First Succession War, pp. 24–25: "Inner Sphere - [2786] Map"
  13. Handbook: House Davion, p. 54: "Federated Suns after First Succession War - [2822] Map"
  14. Historical: Liberation of Terra Volume 2, pp. 122–123: "Inner Sphere - [2822] Map"
  15. First Succession War, pp. 112–113: "Inner Sphere - [2822] Map"
  16. Handbook: House Davion, p. 60: "Federated Suns after Second Succession War - [2864] Map"
  17. House Davion (The Federated Suns): "Federated Suns Map - [3025]"
  18. Handbook: House Davion, p. 70: "Federated Suns after Third Succession War - [3025] Map"
  19. Handbook: House Davion, p. 72: "Federated Suns after Fourth Succession War - [3030] Map"
  20. Handbook: House Davion, p. 76: "Federated Suns after War of [3039] - [3040] Map"
  21. Historical: War of 3039, p. 133: "Inner Sphere - [3040] Map"
  22. Era Report: 3052, p. 11: Inner Sphere - [3050] Map
  23. Era Report: 3052, p. 23: Inner Sphere - [3052] Map
  24. Era Report: 3062, p. 11: Inner Sphere - [3057] Map
  25. Handbook: House Davion, p. 78: "Federated Suns after Operation Guerrero [3058]"
  26. The Periphery, 2nd Edition, p. 111: "Taurian Concordat and Tortuga Dominions"
  27. Era Report: 3062, p. 29: Inner Sphere - [3063] Map
  28. Handbook: House Davion, p. 82: "Federated Suns after FedCom Civil War - [3067] Map"
  29. Jihad: Final Reckoning, p. 43: "Inner Sphere - [3067] Map"
  30. Jihad Secrets: The Blake Documents, p. 64: "Inner Sphere - [3075] Map"
  31. Field Report: AFFS, p. 21: "Federated Suns Armed Forces Deployment Map - [August 3079]"
  32. Jihad: Final Reckoning, p. 63: "Inner Sphere - [3081] Map"
  33. Field Manual: 3085, p. vii: "Inner Sphere - [3085] Map"
  34. Era Report: 3145, p. 11: "Inner Sphere - [3135] Map"
  35. Shattered Fortress, p. 31: Euclid not explicitly named but text states that the Combine had claimed "all the worlds" between New Avalon and Palmyra Thumb by this point
  36. Dominions Divided, p. 75
  37. 37.0 37.1 37.2 Dominions Divided, p. 68