245 years ago, the nations and corporations, independent planets, and satellites of the Sol system united into the Solar Union. After centuries of war over diminishing resources, their rulers, boards, and collectives had finally agreed to a network of trade that would benefit them all. To commemorate the dawning of this unified age and its promise of 10,000 years of prosperity, the organization established a single calendar to unite all the worlds, the Solar Calendar, beginning in the year 0000.
It was rapidly becoming clear that no amount of winning would gain more resources than the system already had. In order to gain more resources, they had to come in from outside the solar system. But, while engineers had designed a method of interstellar travel through Lorentz wormholes, no one nation or corporation had the economic power to develop the theory into a technology. The monied powers of the Sol System combined their greatest efforts in the greatest project ever attempted: the foundation of the Terran Transit Authority and its network of transit gates.
Once they did, they began sending out small groups of colonists to planets deemed potentially productive. Interstellar travel was (and remains) expensive, though, taking energy proportionate to the square of the mass of objects being sent. To minimize costs, they kept the number of colonists to a minimum by sending them along with "labor frames" —machines that make it possible for one colonist to do the work of six. The colonists would pay the SU back for their passage and equipment over time by sending back shipments of valuable chemicals, local biota, and the occasional improvement to frame design.
By SC 0100, the Solar Union was entering a period of rapid expansion, with its Terran Transit Authority authorizing the opening of new transit gates constantly across the galaxy. The Sol system itself had two: one orbiting Earth, another orbiting Mars, and two others under construction in orbit of Jupiter and Venus. Those resulting four remain to this day, a lynchpin of the Solar Union's success.
As the galactic survey proceeded, the SU refined their process to find ever more productive planets. As the price of the goods from those planets went down with their abundance, the earlier waves of colonists found themselves on impoverished colonies with no way to pay their return. When the Solar Union found itself with no reason to invest in those colonies further, the colonies found themselves abandoned.
Exacerbating the issue was a growing disagreement on Mars. Divided into two states —the Northern Republic, a Terran trade stopoff on the way to the Jovian satellites, and Southport, a smaller but wealthier nation backed directly with Jovian hydrogen, the two disagreed vehemently on the terraforming future of the planet. The Republic, with its much larger population, reliable value to Earth, and low altitude, found itself directly threatened by the plan and objected with the approval of its Terran friends. Southport, with its smaller, but wealthy population, stood to gain much from an independent Mars with its own ecosystem. When the Republic's armies attacked terraforming systems dropped by Jovian orbiters, they found themselves at war with the forces of nature and those wielding them; once the terraforming process had begun, they had no way to stop it. The Republic flooded in SC 0175, drowning both of its major cities under glacial water. Much of the region's population became vagrant, taking to the shrinking equatorial deserts in caravans as the planet's atmosphere thickened. Those who didn't, found themselves working for anyone who would pay.
In SC 0198 the SU ran into its first major challenge. It discovered a planet called Celiel, rich in biological and chemical resources. The celebration of the incoming colonists was cut short when the biological resources of the planet turned out to include not only an aggressive parasite, but an aggressive and intelligent parasite.
The parasites, calling themselves "Ijad" (the Ijad word for "people"), lived on many of the local lifeforms, becoming full symbiotes when they found the right individual. The Ijad's moral and social life revolved around a religion, one of the central tenets of which was that no individual should control the actions of another they can't touch. Over time, this had become a taboo against any sort of rule from afar, keeping the scale of Ijad societies small and tribal-scale.
When humans, answering to a ruler thousands of light years away, arrived and began sending their food, their materials, and (in one badly-received misunderstanding) families across the galaxy, they found the situation offensive, immoral, and downright sacrilegious.
At first, the humans were unattractive hosts. They acted immorally, were clumsy and ignorant, and dangerously greedy. The Ijad began to resist their presence, sabotaging their equipment and riding the humans' livestock to freedom.
But when prices dropped in SC 0212 upon the discovery of a yet newer, more productive colony and poverty began to set in to the colony, many Ijad found the humans increasingly willing to listen. Several began to see the wisdom of the Ijad way of life, joining their tribes and becoming citizens in their towns. Some met Ijad and eventually bonded with them, while others never became close enough to an Ijad to join. All, though, according to the Ijad, are now people; they act according to their will and in accordance with those in their community, and so act according to the instructions of God.
When one such tribe of colonists and Ijad tried to begin selling on its own terms through the local transit gate, the local police arrived prepared for violence. The act of force was countered by an act of force, with the colonists fighting back with their labor frames. The colonists and Ijad lost that battle, with a dozen killed and twenty imprisoned for interrogation. In months, though, they had adapted the labor frame technologies for Ijad of all species into highly mobile units capable of evening the odds. By the time the Terran Transit Marines arrived through the transit gate, they discovered it completely controlled by local interests. They fought a hard retreat to get their transport back through the transit gate, returning to Solar territory bearing intelligence of an alien invasion.
Over the next ten years, Ijad used their captured transit gate to spread their religion to other abandoned colonies. As it so spread, so grew fear in the halls of the Solar Union. Because of the cost of sending matter through transit gates, they opted for the less expensive option: recruiting from local colonies. In SC 0216, the United Mars Foreign Legion was formed to build self-sustaining militaries of mobile frame units on troublesome colonies. Answering to, trained, and paid by the Solar Union, the UMFL is nonetheless drawn from local populations. They are equipped with mobile frames that can be built and rebuilt from common designs. They use these "standing tanks" to great effect in their efforts to protect the lifeblood of the starving Solar Union.
This did not sit well with the Ijad-indoctrinated local populations under such control. In SC 0240, a UMFL company arrested the popular mayor of the town of Quall for refusing to sell their exports at the SU market price. The subsequent riot ended abruptly when eight mobile frames, built from labor frame parts and painted in matching orange colors, engaged the unprepared Legionnaires in a high-speed, running battle through the streets of Quall. Despite the loss of two of the colonists' frames, the Legionnaires present were all killed or imprisoned in the town jail. Quall is now considered the first appearance of the Free Colonies movement.
Seeing the successes of the Free Colonies (and its discussions of federation) as further expansion of their enemies, many of the Ijad now see no distinction between the Free Colonies and the Solar Union. Those agreeing with the principle now seek to counter, using the now well-understood technologies of the transit gates and mobile frame to begin their own expansion, forcing back those who would rule them from afar.
The year is now SC 0245. The Free Colonies are a force to be reckoned with, working out of cells, the largely leaderless movement uses gates captured from the TTA to spread its ideas and, most recently, military force. The Ijad push out, expanding tribe-by-tribe across the galaxy in the hopes of pushing the humans and their greed-god away. The Solar Union is expanding more slowly than its needs are increasing and desperately needs new and bigger colonies.
Main Source: Mobile Frame Zero: Rapid Attack Rulebook