Edit: several weeks ago, a combination of a cold, and lack of sleep made me so lethargic I could no longer write. And then I had an Oral Surgery. I will have another next week. And that... well for one, I'm dropping from this compatition. So yeah, sorry. Second, while I will eventually return to this story, It will be a while. Everyone makes mistakes. It's a simple fact the of imperfect intelligent lifeforms that call the universe home. For its part, Humanity had several mistakes of bad assumptions. Like the one about, Newton's third law only allowing rockets in space. The idea that artificial structures would have to be spears shot from one target to another, trailed by the clouds of their jet. The reality, as it turns out, it's about momentum; As long as momentum can be exchanged, acceleration can happen.  Which does not necessarily mean catching or tossing mass. They also thought wrongly about the matter of artificial gravity. True, they were onto something when it came to spin being able to emulate gravity, but they flubbed the finer assumptions. "Space ships, once spin gravity becomes common, will *have* to use low spin for the sake of the hull, at least for the first centuries... Thus humanity will have to adapt to lower gravity," was how they thought. Turns out though, that with active support, thicker heavier hulls are allowed. And these thicker, heavier, reinforced hulls not only allow to use a much higher spin, by being heave, they contribute gravity themselves. More so when the spin gravity itself is used as a flywheel battery to feed those active supports proportionally. After all a thick heavy hull carries a lot of momentum. Momentum that can be used to generate far more power, with less spins lost. That was before factoring in the discovery that Spin Gravity itself could be manipulated into a forward momentum. Thus humanity adapted to a greater variation in gravity. The greatest mistake of humanity though, was one of humility. They assumed that an old space faring species with all that implies, will wipe the floor with them. Thus, their expansion, though notable enough, wasn't that of a dedicated colonial effort, just a fringe expansion area made up of a tiny portion of the species. Humble, but big enough to be seen if someone or something happened to be looking. But as it turned out, their Solar System is actually one of the more Busy Solar systems while holding A Sapient species. Busy enough that every ship they sent, that was meant to stay in the black, had more firepower than just its speed and mass. Civilian or not, asteroids, large and small were everywhere. And the little thing of Gravity. Earths are pretty big. When an organism on Earth falls down, they must process that information very fast or they crash. Thus, the very time perception of humans… is fast and thorough.  The Seliny Christal Empire's great mistake, though, was one of Hubris. They were a dedicated colonial species, spanning far and wide across the cosmos. Their wonders and works visible to all, their presence felt, and their primacy seemingly all-mighty. In their own eyes. They were world-shapers, and didn't see the need for permanent mobile habitats; not when they could bend the rocky moons and planets of any and every system into something habitable. They measured their power by colonized habitable worlds and systems in their possession alone. Thus they measured by a similar metric all races in space. Lucky for them, all those species, like them, Evolved around the red dwarfs, on worlds that held their air more by electromagnetism than gravity. The Empire was the first to see Humanity, it's first toes dipped into the great ocean that was space, screaming into the void as loudly as the day it was born. Their scouts followed those cries back to Humanity's cradle system, and upon a glance they found Humanity wanting. They were sure that a species less than fifty years after its first private owed space habitat came into use, as the data mining of the Sol Info-Aura showed, would never be able to put up a fight. The Empire was meticulous in all it did, a side effect of having a long lifespan. Their Empire was born during a time of shorter lifespans, back when they were more akin to a dog in life expectancy than a human. Those days had come and passed, as they did with every great space civilization in the galaxy, with life extension. The Empire was merely the most recent great power, in a long line of great space powers, to extend their life span into the hundreds of years; the most recent to usurp power from the decadent races prior, content to sit on their laurels and past victories. The Empire though, hadn't stopped like those powers had, merely slowed, but that was enough. Turns out, a species that evolved under low gravity, with a fairly slow time perception, comparable birth rate or not, should not start fights with a species that... Is fairly not. Even if the space assets it has in place are not quite a percent of of the fleet you are sending their way.