Battle of Renatasia

The Battle of Renatasia was an Imperial/Centrality "victory" in 12 BBY that saw the conquest of the Renatasia system, one of the many lost Human colonies founded by Grizmallt under the Old Republic.

Prologue
In 13 BBY, the lost Human colonists of the Renatasia system were rediscovered by the Centrality. Osuno Whett and Vuffi Raa were assigned by the Centrality and the Galactic Empire to win the trust of the Renatasians to make them easy targets for the armed forces to subdue. Covering the droid Vuffi Raa with an organic exterior, he posed as Vuffi's assistant and presented them as representatives of a galactic civilization eager to welcome the Renatasians.

After 700 days of celebration, Whett transmitted all his data, beginning the invasion by the Imperial and Centran forces.

The battle
Unfortunately, the two interstellar governments had overlooked one thing. Until Whett arranged for them to unite, Renatasians had been ruled by multiple, competing governments (whereas most systems that were forced to join the Empire had fallen under one governing body for quite some time). As such, the Renatasians were used to combat and excelled at it.

Uniting against the Empire and the Centrality, the native population was able to slaughter 93% of the original occupying force. The first wave of reinforcements suffered 87% losses, the second 71%, and so on, despite the Renatasians' technological disadvantages; they knew how to fight and they did it well.

The Imperial-Centran forces stepped up their response, and as the war waged on it turned into one of the bloodiest, most brutal conflicts the Empire had ever seen.

Aftermath
It is estimated that approximately two-thirds of the Rentasians perished. Even long-time, hardened soldiers were horrified; the battle for Renatasia had been brutal even by Imperial standards, and they along with the Centrality tried to cover it up as best they could.

Afterward, Vuffi Raa was nicknamed the "Butcher of Renatasia" since none of the Renatasians realized he was a droid and that Whett was the true butcher. In response, a group of the survivors had commandeered some aging starfighters and vowed to hunt down and kill Vuffi Raa.