[Coffee Warlord]

I give to you, the Restored Roman Empire's subjugation of the Lohlendran Watchers. (Stellaris)

The Empire made first contact with this once mighty empire not long after their first forays into space. The Lohlendran were deep spiritualists, diametrically opposed to the staunch Roman faith in science and technology. That said, so long as Rome did not colonize worlds the Watchers declared Holy Worlds, they were left alone.

Centuries passed, and Rome grew strong. Their borders reached the Lohlendrans, and eventually, Rome no longer cared for the warnings of these decrepit fools. They colonized these so-called 'Holy Worlds', and the response was quick, but Rome was ready. Massive fleets clashed, and Rome was victorious.

The fleets moved into Lohlendran space, demolishing the ancient automated defenses left there. Their fleets blanketed every planet, commencing bombardment on an epic scale. For years, Roman ships bombarded these religious lunatics from space, turning their proud worlds into dusty ruins. Those soldiers who survived were met with genetically engineered monsters, slaughtering ever Lohlendran soldier encountered. This once mighty empire was compelled to surrender to Rome.

But Rome was not finished with these people. Too many humans died to simply leave this arrogant wretches alive. A policy of depopulation began, as the survivors were forcibly evicted from their homes, out of Roman space, where they would survive as they could as refugees. A full 2/3rds of the Lohlendran survivors were removed from their native worlds.

The remainder were taken to Roman labs, to be genetically modified. They would be made more suitable for low level labor, to serve in the mines and farms to fuel the Roman war machine. They were conditioned to serve, to see themselves as a proud cog in the service of humanity. They were also modified to survive in the cooler, more temperate climates that humanity preferred, away from the dry, hot savannah worlds they originated. Just one Lolendran planet was left under their control, a tiny colony on the edge of Roman space, which had little tactical value. Rome was content to leave them be, the message clearly sent.

Time passed. The Lolendran refugees, a once mighty empire that spanned the galaxy, with untold technological mastery, surfaced again....as nothing more than a small criminal cartel far away from their homelands. That, and the one colony that was allowed to survive, was all that remained of these people....not counting those who were genetically altered, of course. The Lohlendran planets were terraformed away from the unpleasant Savannah, and made into worlds more suitable for human life. Little remains to show that an ancient power ever stood on these worlds.

But Rome was not done. Oh no, no no. But it was not Rome that chose what would happen next.

The remains of the Lohlendran Watchers, clutching to their last hope on a small planet, declared war, a last ditch effort to free their homeworld. It was doomed from the start, but the price would be high. People must know when they are conquered. Rome came, landing millions of troops, conquering the last true Lohlendran world, forcing total capitulation. This time, there would be no mercy.

Purges began anew. Every Lohlendran would be purged from this final planet, save a tiny few. Every structure was reduced to rubble, and the planet itself was met by Roman terraforming engines, turning the planet from a warm Savannah plain to a frozen Arctic world. Those few Lohlendrans who remained were forced to huddle in squalor, on a frozen world that was their last refuge.

Rome was not done.

The fleets came once more, but this time, this planet would become the testing ground for their new ultimate weapon. The Lohlendrans, freezing and starving on their desolate frozen waste, looked to the sky to see a massive ship. A bright flash in the skies above, and a massive energy weapon came crashing down, utterly destroying the planet, leaving nothing but a small field of asteroids and debris where a planet once stood.

And thus the war was over. Roma Victor.

To summarize:

1) We defeated and conquered all but one Fallen Empire world.
2) We displaced about 200 of the 300 members of their race.
3) They popped up not long after as a Criminal Syndicate halfway across the galaxy.
4) We genetically modified those we kept to be laborers, and terraformed their worlds.
5) They declared war again, we crushed them.
6) We purged all but 1 of their people from that world after we won.
7) We terraformed it to Arctic, because that was as far away from Savannah I could think of, just to be an ass.
8) We released them as a vassal, freed them, and declared war.
9) And then sent the planet cracker in, and destroyed the planet.