Unable to resist the seemingly mythical powers of the Jedi Knights, and the armies of loyal soldiers they commanded, in desperation the ambitious leader of the Galactic Senate, the ageing Senator Palpatine, convinced the Republic President to turn to the only force capable of resisting the Jedi: their long-exiled heretic brothers, the Sith Order.
Once merely the political faction of the Jedi, granted unique freedoms from their strict code, the Knights of the Sith grew into a shadowy organisation separate from the main body, acting often under their own direction and energies, engaged in operations for which the Jedi themselves had no stomach.
Yet even the Jedi were not entirely immune from scandal, and when a string of failed Sith suppressions and assassinations became publicly known, the Sith Order, as they had since become, were stricken from the Core Worlds - the Republic itself - on pain of death, banished to insignificance in the furthest reaches of space.
For centuries the Sith lurked on the fringes of the Outer Rim, from their shrine-worlds of Korriban and Ossus. Ever they plotted their return to the Core World of Had Abaddon, where they had once, many hundreds of years ago, been as influential as the Jedi.
Yet the vanishment of the Sith had even at that time caused a great scission within the Jedi Order itself, and while few on the Council legitimately mourned their exile, many of the Jedi whose task saw them overseeing planets with powerful Senators, wealthy corporations, or ties to underhanded criminal syndicates, recognised the value, and regretted the loss, of the Sith for their capabilities against hostile forces who did not adhere to the same code as the Jedi or, worse, whose own ethics specifically undermined the strength of the Jedi way. After all, the Sith had been created as an aberration to counter the presence of particularly brutal or underhanded opponents, precisely so that the Jedi themselves would not have to.
As the ranks of the Jedi had shrunk through war, so had the Sith expanded over time. Never as numerous as the Jedi, the Sith were now of a similar strength to their kin, a force to be reckoned with, even after the recent experiments with clone technology. Formally recognised by the Republic once more, the Sith returned.
And burned upon their every thought was one solitary, raging mission: vengeance.
From the resurgent fortress-world of Had Abaddon, homeworld of their ancestors and recently bestowed upon them by grateful Republic leaders, the Sith fought back against the Jedi at the head of the Republic armies. As the galaxy slipped further into the chaos of war, Palpatine grasped an opportunity to usurp the Presidency and solidify his own personal power. As architect of the expulsion of the Jedi, his was a populist platform irresistible in the throes of the Clone Wars.
Soon, the President turned his attention to removing the last legal vestiges of the Jedi Order. The Galactic Senate, in its haste to be done with the terrible Clone Wars, recreated the Jedi as criminals and heretics, terrorists against the great Republic. Magicians and witches, they became quickly despised, figureheads of ridicule, scapegoats for every social ill that swept the Republic. Further increases to the strength of Republic navies, the swelling of armies, and increases to surveillance and security followed. Bloated with pride, the Republic saw the end to all its ills in the shape of the Jedi Order, welcomed the much-maligned Sith as saviours, and for the briefest time truly believed the hubris of the expulsion would bring peace once more. For a time, it seemed a brilliant tactical manoeuvre; the corpus of cost sacrificed upon the grand altar of expediency.
Within the space of a few years, the entire doctrinal foundation of the Republic, based as it was upon the rule of law and justice and the enforcement of that law by its champions the Jedi, was irrevocably altered.
The Galactic Empire was born.
From the ashes of the Second Clone War arose a great shadow, and its name was Darth Vader. Among the mightiest of the Sith Lords, Vader held a special place in the history of both ancient Orders, for he had once been apprenticed to the Jedi - then exiled - and latterly become a Dark Lord of the Sith. Reviled by many on both sides as a traitor, an unreliable actor whose half-mechanical body was the perfect symbol of his inhumanity and inconstancy, Vader might have himself become a pariah but for the nature of his unique talents and the means by which he deployed them.
A military commander without peer, Vader oversaw the turning of the tide. Most Imperial scholars would later identify the Battle of Hoth as the final defeat which broke the will of the Jedi Order, yet in truth it was a succession of brilliant victories which allowed Vader, among other Sith Lords, to bring the Jedi to their knees.
In full retreat, the Jedi gathered at Tython for one final stand, where they desperately attempted to manufacture a literal means of retaliation. To no avail, an enormous Imperial Star Fleet arrived at the planet, and left it in ruins.
For the galaxy at large, that moment heralded the end of the Clone Wars. With the extinction of the Jedi, the New Order was established and peace returned to the Core Worlds of the Old Republic, now the Galactic Empire.
Celebrations began across the wealthy inner worlds of the new Empire, and its new ruler and Emperor, Palpatine, became a hero - the man who ended the war. The people of the Old Republic turned a blind eye to his abuses of privilege and law during the crisis, and embraced the new safety and order of the Empire.