The Galactic Civil War is a fictional war from the Star Wars galaxy. It serves as the setting for the original trilogy of films A New Hope, The Empire Strikes Back, and Return of the Jedi, as well as many novels, comics, and video games in the Expanded Universe.
The war was fought between the Galactic Empire and Rebel Alliance, later renamed the New Galactic Republic. While it is hard to pinpoint exactly when the war itself began in earnest (although it was surely in full swing shortly prior to the events of A New Hope), the foundations of the conflict are depicted during the events of Revenge of the Sith.
During his rise to power in the waning days of the Old Republic, some Senators became alarmed at the centralization of power in Palpatine's hands. With his Sector Governance Decree, issued shortly before the end of the Clone Wars, Palpatine was able to render the Senate virtually powerless. He was given the power to personally appoint governors to rule various regions of the galaxy; while they were nominally subordinate to the Senate, in reality, they answered only to Palpatine himself. Since Palpatine could personally appoint them, he would fill the positions with only the most loyal men.
As shown in the novelization for Revenge of the Sith, in response to the decree, nearly two thousand Senators, including influential Senators such as Bail Organa, Mon Mothma and Padmé Amidala, issued a petition requesting that Palpatine restore the Senate to power.(although in the deleted scenes of the DVD Revenge of the Sith, we do see the senators thinking about the rebellion). Palpatine not only ignored the request, but would eventually order the arrest of many of the signatories, denouncing them as traitors. Those who were not arrested were forced to openly support Palpatine's policies; however, these Senators were able to begin covertly plotting against Palpatine and the new Galactic Empire. That event, as well as the Great Jedi Purge--the near-elimination of the Old Jedi Order (as orchestrated by Darth Sidious and Anakin Skywalker--who by that time had become Darth Vader) that followed--helped set the stage for the Civil War.
The Galactic Civil War arguably began with the issuing of Order 66 and the start of the Great Jedi Purge, although it is not clear that there was any significant organised armed resistance to the rule of the Empire until the signing of the Corellian Treaty by former Republic senators Mon Mothma, Bail Organa and Garm Bel Iblis less than 2 years before the Battle of Yavin, which detailed their grievances against Palpatine, and proclaimed their decision to overthrow him. The war initially began with the Empire in control of most of the galaxy, and in command of a vast military; the Alliance by comparison had few resources and forces, and was consistently defeated in every straight battle in the early years of the war.
The Rebel Alliance was first discovered by the Empire shortly before the Battle of Danuta. The Empire captured and imprisoned many rebels for questioning and torture in the Death Star. The Rebels escaped their cells and caused an uprising in the battlestation. While most of the rebels were killed, several managed to escape with a partial set of the Death Star plans. These rebels took refuge on Polis Massa, the original base of the Alliance. The 501st division of stormtroopers raided the base, believing that they had destroyed the plans. However, the rebels managed to transmit the plans to another rebel group. Eventually they reached the Tantive IV, a rebel ship flying under diplomatic immunity. Combined with the plans stolen at Danuta, the Rebels were able to find a weakness in the Death Star, destroying it at the Battle of Yavin. Prior to this battle however, the Death Star was used in the destruction of the planet Alderaan as a strategy to draw out the real rebel base of Yavin IV. The planet's destruction claimed about two billion lives, including that of the influential Senator Bail Organa.
Despite their great success at Yavin IV, as stated in the opening of The Empire Strikes Back the Rebels then suffered a "dark time"; although the Death Star had been destroyed, the Imperial army and navy were vast and remained intact. The Alliance was forced to relocate from Yavin and to flee for the next three years while the Imperial military chased them across the galaxy. Eventually they were able to set up a new base on the planet Hoth; however, the new base was soon discovered by the Empire, and was subsequently destroyed in the Battle of Hoth. After the battle, the surviving Rebel forces were forced to remain ship-borne at the outskirts of the galaxy (as seen at the end of The Empire Strikes Back).
The Rebel Alliance benefitted from the oppression of the Empire in a way, as many disaffected individuals defected to their side. Skilled commanders from the Old Republic such as Jan Dodonna led the Alliance military, notably at the Battle of Yavin. The defection of the Incom Corporation provided the Alliance with the valuable X-wing fighter. In the Expanded Universe, it is stated that the Empire was strongly racist towards non-humans, even going to far as to enslave races such as the Wookiees, meaning some of these non-human races became dedicated to the Alliance.
Darth Sidious was able to use the emergence of the Alliance as a threat to further his own power, a cunning ability he had demonstrated in the past. After the events of Danuta, Sidious ordered the final disbanding of the Senate, allowing his governors to have direct control over their territories. The Imperial military was further enlarged, with ever more powerful weapons and ships being invented.
With Jedi-in-training Luke Skywalker's pivotal role in the Battle of Yavin, he was deemed a major threat by Sidious; as a Sith Lord, only a Jedi could truly threaten his reign and Luke eventually showed he had the potential to be a powerful one like his father. In The Empire Strikes Back, Sidious and his servant Darth Vader agreed that Skywalker should join them or be killed. At Bespin, however, Vader revealed that he is actually Skywalker's father, and plotted to ally with Skywalker in order to overthrow Palpatine. Although Skywalker ultimately refuses the offer, Vader's relationship with Skywalker would later play a major role in the downfall of the Empire.
Following the destruction of the Death Star at Yavin, the Empire began construction on a second, more powerful Death Star. Still in its construction stages, yet having its weapons operational and being protected by an energy field generated from the moon it was orbiting (called Endor), this second Death Star was attacked by the Rebel Alliance.
Although Sidious had allowed the Rebels to learn of the Death Star, its incomplete status, and the nature of its defenses (short of the operational main weapon), he failed to plan for the attack of the indigenous Ewoks, which allowed the Rebels to destroy the defensive shield, as for the Rebel commanders, somehow protected their fleet from the Death Star's main weapon by engaging the nearby Imperial fleet up close but came under heavy fire and much of the fleet was destroyed by this "strategic" move. The Battle of Endor was a victory for the Rebel Alliance. Darth Sidious died, as did Darth Vader; the large Imperial fleet present at the battle was scattered, and the incomplete Death Star was destroyed.
In the aftermath of the Battle of Endor, people around the galaxy celebrated the end of Imperial power, including the people of Coruscant, formerly the Imperial capital. One explanation of this quick wind-up of the war, would be that the Imperial soldier (whom George Lucas has identified as being clones [Starlog magazine issue # 300 page 42- 43], thus with the same follower of the Clone troopers) simply obeyed the orders of those they deemed to be next in line of authority: a newly recreated Senate. Such a "rapid" recreation of government would be consistent with the patient long-term planning seen in the character of former Senator Mon Mothma.
The Expanded Universe details many more battles of the conflict, such as Prince Xizor's involvement in the Civil War. Many of these events can be found in the timeline below.
Further, the Galactic Civil War continued after the Battle of Endor for many years in the Expanded Universe. With the destruction of the Galactic Empire's central leadership, the institution fell into warlordism, becoming disorganized and weak. Even so, the Empire remained a formidable threat to the New Republic, as it controlled much of the galaxy and still had access to a powerful military. In an effort to fully restore the galaxy to a peaceful state, the New Republic began a campaign of recapturing vital Imperial worlds, including Coruscant, the former capital of the Old Republic and the Galactic Empire alike. The Empire rose again several times under powerful leaders such as Grand Admiral Thrawn and a series of clones of Palpatine, but was always thwarted when those leaders were killed.
Later, a peace treaty was finally signed between the New Republic and the tiny fraction of the galaxy that was under the control of what remained of the Empire, nineteen years after the Rebels' victory at Yavin. At this time the Imperial Remnant, led by Grand Admiral Gilad Pellaeon, consisted of eight backwater sectors bordering the Unknown Regions in the Outer Rim. These systems preferred the policies of the New Order rather than those of the New Republic.
The following is a timeline of the Galactic Civil War. Note that most of these battles are summarized in the plot synopsis of their respective video game or book article. Dates may not be exact.
Although "STRIKE FEAR" isn't mentioned in the Star Wars films, it is mentioned in the Star Wars: the Essential Chronology and the aforementioned Star Wars: X-wing game.