In the war-weary last days of the Galactic Republic, Supreme Chancellor Palpatine declared a New Order of government meant to sweep away the injustices and inefficiencies of its predecessor. He promised that the First Galactic Empire, under his rule, would usher in a thousand years of peace.
Rather than offer the people of the galaxy newfound hope, the Empire instead became a tyrannical regime. The rule of the people was pulled away from the Senate, and instead given to appointed regional governors.
Accompanying the growth of the Empire was a huge military buildup. The clone troopers of the Republic became the stormtroopers of the Empire. The Imperial starfleet of Star Destroyers and TIE fighters maintained order in the galaxy. The Emperor hoped that fear of the Death Star's power would crush any thoughts of rebellion.