The Sanctuary Pipeline represented a highly classified hyperspace route that the Galactic Empire engineered and maintained. This was achieved after they deployed S-thread boosters to counteract the gravitational disturbances that had caused a pre-existing hyperlane to collapse. This route provided a direct connection between the planet of Sullust and the moon known as Endor. The Empire leveraged this secret passage to discreetly transport supplies for the clandestine construction of a second Death Star superweapon.
Around 4 ABY, Galactic Emperor Palpatine deliberately leaked information regarding the new Death Star to the Rebel Alliance. The rebels then analyzed the Sanctuary Pipeline and resolved to exploit it for a surprise assault on the superweapon. Sullust was chosen as the assembly point for a growing Alliance fleet. These Alliance forces subsequently utilized the route to launch their attack on the Death Star orbiting Endor, only to discover that the Emperor had orchestrated a trap, concealing his own fleet there. Despite this ambush, the ensuing battle culminated in the destruction of the superweapon and the death of Palpatine.
The Sanctuary Pipeline was an artificially constructed hyperspace route that followed a straight path from the planet Sullust located within the Outer Rim's Sullust sector, to the forest moon of Endor situated in the Outer Rim's Moddell sector, traversing the Mid Rim Territories. Its creation served as a replacement for a former hyperlane that had been displaced due to galactic drift. S-thread boosters were employed to rectify gravitational inconsistencies and reinforce the collapsed pathway. Before reaching Endor, the Sanctuary Pipeline passed through Murk within the Moddell sector. The route intersected with the Rimma Trade Route and Incisor Sidestep at Sullust, and also the Bakura Trace near Endor.
The Galactic Empire was responsible for the creation of the Sanctuary Pipeline, investing a significant amount of resources into S-thread boosters to both re-establish and maintain the hyperlane. This route was shrouded in secrecy, its primary function being to channel construction materials to Endor, which the Empire referred to as the "Sanctuary Moon," without attracting attention from the rest of the galaxy. The supplies transported to the Endor system were intended for the construction of the Death Star II superweapon, a successor to the Death Star that had been destroyed by the Rebel Alliance during the Battle of Yavin. Thousands of cargo transports moved supplies to the construction site via the Sanctuary Pipeline, with Venator-class Star Destroyers among the starships used to safeguard the clandestine route.
Around 4 ABY, Emperor Palpatine conceived a strategy to lure the majority of the Alliance's forces into an ambush by disseminating information about the new Death Star to the Alliance. Following rumors originating from the Moddell sector, the Alliance collaborated with the Bothan Spynet in an intelligence operation orchestrated by rebel General Crix Madine. This operation led to the Bothans uncovering the existence and location of the second Death Star. The navigational data for the Sanctuary Pipeline was also intentionally leaked to the Alliance, where it was analyzed by Major Capin Harinar. Harinar's analysis allowed him to correctly determine the true purpose of the Empire's secret route.
During an Alliance High Command summit on the planet Zastiga, Admiral Gial Ackbar shared the news of the new Death Star with key Alliance leaders and provided detailed information about the Sanctuary Pipeline. Many rebel leaders were impressed by the technology used to maintain the route's integrity, acknowledging that such an undertaking would typically bankrupt multiple star systems while still costing less than building a Death Star.
As the Alliance planned a large-scale attack on the second Death Star, Corporal Ractivelle presented a report on the Moddell sector and the known routes to reach the Death Star, concluding that it would be impossible to reach the battle site undetected using established routes. However, Harinar proposed in a classified document on the Sanctuary Pipeline to Madine, that the secret route offered the best chance of surprising the Empire. Ackbar concurred, and in an official document to Alliance Commander-in-Chief Mon Mothma he suggested Sullust as a staging area. He reasoned that the Alliance's previous involvement with the planet during Operation Ringbreaker would lead the Empire to believe that the rebels were simply seeking further conflict there. The reports concerning the Sanctuary Pipeline between the Alliance figures were compiled by Mothma's aide and archivist Hendri Underholt, who included them in his archive of non-electronic Alliance documents titled The Rebel Files.
The Alliance fleet gathered in the Sullust system in preparation to jump through the Sanctuary Pipeline and strike at the Death Star. Simultaneously, at the other end of the route, Palpatine prepared his own trap, concealing a substantial Imperial fleet behind Endor. When the Alliance fleet jumped through the Sanctuary Pipeline and launched its assault, the Emperor's hidden fleet emerged and flanked the rebels, resulting in a significant engagement. However, the Emperor's plan failed when the Death Star's shield was disabled by rebel ground forces, allowing rebel starfighters to penetrate and destroy the superweapon. Palpatine was killed onboard the superweapon during the battle.
Around the same day as the Battle of Endor, Underholt was killed during the Empire's bombardment of the Tak-Beam complex on the planet Durkteel, resulting in The Rebel Files being buried. The archive was recovered during an excavation in 34 ABY and came into the possession of the Resistance, a private military organization with ties to the Alliance, formed to oppose the Empire's successor, the First Order. Resistance Admiral Ushos O. Statura annotated Harinar's document on the Sanctuary Pipeline, questioning whether the First Order might be using S-thread boosters to navigate the Unknown Regions.
The Sanctuary Pipeline made its debut in Richard Marquand's 1983 film Star Wars: Episode VI Return of the Jedi, which served as the concluding chapter in the Original trilogy of Star Wars.