First Caal Invasion
Second Caal Invasion
A large force of Caal, seeking The Orb, invaded the Earth Federation in 2264, completely eradicating the populations of Edo, Khmer, Pyong, Hadley, and Jennifer's Star, but then bypassing Wilke's Star and New Paris to attack Avalon itself. In orbit above Avalon, the fleet of captured ships transporting the Caal and their possessed hosts was fought and ultimately destroyed by a joint force of Earth Fleet and Horadrim warships, with asssistance from Vin Dane wielding The Orb. When nearly all the allied warships perished in the battle, credit for the victory fell almost exclusively on Vin Dane's shoulders.
Behind the Scenes
The Caal were inspired directly by the movie Fallen with Denzel Washington, and of course similar beings exist in many other fantasy and science-fictions stories, notably Passengers by Robert C. Silverberg, and the final episode of the Babylon 5 spinoff series Crusade.
Season 9 (WIP)
Hundreds of millennia ago, the Caal were mortal beings whose physical bodies aged and died like any other species. Their civilization was highly disciplined and rigidly hierarchical. Their culture was relatively inward-looking, and prior to the great calamity, the Caal never wasted many resources exploring beyond their own homeworld. Despite this, they developed technology well beyond anything made by modern humans and even, in some respects, more advanced than the Horadrim.
Eventually, Caal scientists even believed they had discovered the solutions to true immortality, of both body and spirit. It was not an elegant solution, but the science did seem to point to the possibility of constructing a device that, wielding enough brute-force power, could enable the transcendence of the entire species.
The Caal's rulers ordered its immediate construction. No expense, in either manpower or raw materials, was spared to build the largest, most complicated, most powerful single machine in their history. Thousands of Caal were worked to death in order to complete the device as quickly as possible. The tremendous sacrifice was deemed worthy due to the project's final goal of immortality.
And when it was complete, and the device activated, the Caal became immortal. Unfortunately, the Caal's theoreticians had misunderstood the full implications of their work. While the spirit of every Caal did indeed become ageless and immortal, the Caal also lost their mortal bodies and all but the most tenuous link to the physical world.
Without the ability to touch their world or their tools, and unable to work even the simplest magick, every one of the Caal was rendered utterly helpless. The entire race wallowed in misery for millennia on end. A ferocious insanity had long since set in among the wraiths by the time explorers of another species finally set foot on the Caal homeworld.
Metaphysics and Technology
Prior to their fall, the Caal developed a deep understanding of natural laws unifying both "magick" and mundane physics at which humanity's most accomplished technomages have barely begun to scratch. Caal scientists could describe the operation of an arcane ritual as comfortably and with as much precision as they could that of a printed circuit board. With the correct diagrams, Caal scholars might capture the complete nature of spells, spirits, or even gods. They perceive nothing as mystical, and the only differences are the degrees of complexity involved.
Fundamental to the Caal theories of everything are two "forces": patternism and entrophism.
Patternism encompasses just about everything described by the human and Horadrim sciences. Matter and antimatter are patternistic phenomena; gravity and electricity are patternistic forces. Most of known reality and explored space are entirely patternistic.
Entrophism is essentially the antithesis of patternism, an opposing force. It is most apparent in the working of magick, when patternistic entitities are destroyed or degraded in order to be replaced or reformed. Entrophism is the force by which all patternistic creations and phenomena are eventually undone. It is why the Caal remained mortal even with advanced medicines capable of preserving their physical bodies indefinitely: the entrophic element of their nature still ultimately wore down and unmade their souls.