Rather than offer the people of the galaxy newfound hope, the Empire instead became a tyrannical regime, presided over by a shadowy and detached despot steeped in the dark side of the Force. Personal liberties were crushed, and the governance of everyday affairs was pulled away from the senate, and instead given to unscrupulous regional governors.
Accompanying the growth of the Empire was an unprecedented military buildup. The many shipyards in the Emperor's domain churned out immense fleets of Star Destroyers and TIE fighters. The Imperial starfleet maintained order in the galaxy, a role previously undertaken by the Jedi Knights, an august order of protectors wiped out during the Emperor's ascent.
It was through fear that the Empire ruled. Its power hungry lieutenants and technocrats developed greater and greater instruments of destruction to cow a rebellious populace. This philosophy culminated in the creation of the Death Star, a mobile space station with a prime weapon of unspeakable power. When fully charged, the Death Star's superlaser had the ability to destroy a planet.
Despite such shows of strength -- indeed, because of them -- the flames of rebellion fanned higher. Small pockets of resistance banded together to form the Alliance to Restore the Republic. At first, the pitiable number of freedom fighters seemed no match for the oppressive Empire. Nonetheless, they managed to score an impressive victory with the destruction of the Death Star at the Battle of Yavin.
Having proved itself a viable threat, the Rebel Alliance found itself under Imperial counterattack. The core group of Rebels spent three years relocating their hidden headquarters, before being routed in a crushing attack at the Battle of Hoth. A few short months later, the Rebels discovered that the Death Star was but the first of many Imperial superweapons in development. A second Death Star was nearing completion over the distant moon of Endor. Intelligence gathered by Bothan spies informed the Rebel planners that Emperor Palpatine himself would be present to oversee the final stages of construction.
Thus an irresistible target was in place over that peaceful green moon: the Empire's next great weapon, incomplete and vulnerable, and the head of the Empire himself, both in one place. The Alliance took the bait -- the Battle of Endor was entirely designed by the prescient Emperor Palpatine to be the final confrontation in the Galactic Civil War. Palpatine failed to foresee the resourcefulness of the Rebels or the treachery of one of his most trusted aides, however.
Palpatine died at Endor, and the second Death Star was destroyed. With this crippling blow, the Imperial reign of terror over the galaxy ended. The Rebellion began forming a New Republic, and worlds across the galaxy celebrated their newfound freedom.