Interdictor vessels, or simply Interdictors were terms for a type of starship employed by the Galactic Empire with the technology to generate a gravity well, which had the capability to pull vessels out of hyperspace as well as preventing them from entering it. Interdictor vessels could be from various starship classes, ranging from frigates to Star Destroyers.
An Interdictor vessel, or simply an Interdictor, was a type of warship that was capable of of blocking starships from entering hyperspace, or pulling them back into realspace using gravity well projectors that created artificial mass shadows. Gravity well projectors were circular in shape, with multiple Interdictor models being equipped with four projectors. There were also multiple models of Interdictors within different starship classifications, including Star Destroyer, heavy cruiser, cruiser, and frigate.
One of the earlier Interdictor models during the Imperial Era was the Detainer CC-2200 cruiser, which was characterized by stubbed wing-ling lateral projections that housed four gravity well projectors. It was also designed with thick armor and a down-sloping bow and sublight engines. The CC-7700 frigate shared these characteristics, but was an updated version of the older CC-2200. The Immobilizer 418 cruiser was 600 meters in length, and was equipped with four spherical gravity well projectors on its hull. It also carried a complement of twenty-four TIE fighter series craft and was armed with twenty laser cannons. At the time of the Immobilizer's introduction, it was plagued with multiple technical issues despite its design being state-of-the-art.
The Interdictor-class heavy cruiser was an evolution of the Immobilizer, and had a delta wing-shaped design with four spherical gravity well projectors on its hull. These projectors were vulnerable, with their destruction being capable of compromising the entire vessel. Eventually, both the Immobilizer and Interdictor-class cruiser were phased out of manufacturing and replaced by the Interdictor-class Star Destroyer. Derived from the standard Imperial-class Star Destroyer, it measured at 1,600 meters in length and was considered better protected.
Interdictor vessels were deployed to generate interdiction fields to pull enemy ships out of hyperspace or prevent them from entering it to begin with. With these capabilities, Interdictors blockaded worlds, investigated suspicious hyperspace routes, and could form part of small battle groups or task forces to support heavier lines of capital ships while working with frigates and starfighters. Interdictors were placed in key locations along their patrol routes and capture ships from hyperspace to board them for inspection as well. Interdictors could also act with an escort, but in times of desperation could operate without one.
For hundreds of years the technology of gravity well projectors required a large, immobile power source. As such, Interdictor vessels could not be developed. During this period of time, gravity well technology was chiefly used to prevent travel near vital installations. However, this changed from research conducted during the Clone Wars, which led to more efficient projectors, and Imperial field tests with gravity well projectors mounted onto a space going vessel. Following the Clone Wars and into the Imperial Era, Interdictor vessels were used by the Imperial Navy to control hyperspace traffic, although the technology remained limited. By 14 BBY, during the Berch Teller campaign, Imperial Vice Admiral Dodd Rancit suggested using Interdictors to pull the hijacked personal vessel of Moff Wilhuff Tarkin, the Carrion Spike. The task force used a trio of Interdictor vessels, including an older Detainer CC-2200 cruiser, a newer CC-7700 frigate, and a newly developed and untested Immobilizer 418 cruiser, which was developed for the Deep Core Security Zone.
The task force activated their Interdictor vessels to capture the Carrion Spike corvette in the Obroa-skai system, however the Interdictors failed and created an incident in which multiple civilian craft were pulled out of hyperspace, resulting in civilian casualties. The Immobilizer was dispatched back to the Corellian Engineering Corporation to correct its operational issues.
By 4 BBY, a prototype Interdictor-class heavy cruiser, the Interdictor, was active in the Del Zennis system under the command of Admiral Brom Titus as it underwent examination. The Interdictor-class cruiser was an evolution of the Immobilizer 418 cruiser, and part of the Interdictor line which included a combat refit, a suppression refit, and an experimental refit. The Interdictor operated alongside two other Interdictor cruisers, pulling a CR90 corvette out of hyperspace. The Interdictor eventually captured the rebel corvette Liberator and its crew, including Commander Jun Sato and Ezra Bridger. During a rescue attempt by other Phoenix Cell members, the Interdictor and its escorting Arquitens-class command cruisers were destroyed.
During the Lothal campaign's culmination with the Battle of Atollon in 2 BBY, Grand Admiral Thrawn deployed two Interdictor-class cruisers along six Imperial-class Star Destroyers of the 7th Fleet to capture Rebel Alliance leadership and destroy Phoenix Cell and Massassi Group. One Interdictor was commanded by Admiral Kassius Konstantine, but was destroyed when Commander Sato sacrificed himself and his flagship, the Quasar Fire-class cruiser-carrier Phoenix Nest, by ramming the Interdictor. This created an opening for a rebel ship flown by Ezra Bridger to escape and warn others. The other cruiser, the Constrainer, was destroyed when rebel Mandalorian reinforcements arrived from behind the 7th Fleet's formation, ambushing the Constrainer and destroying it with rockets. With both Interdictors destroyed, the surviving rebel forces managed to escape the 7th Fleet's blockade of Atollon. Years prior to the Battle of Yavin in 0 BBY, Lando Calrissian and L3-37 were ambushed in the Halthor sector by an Imperial interdictor as they delivered a shipment of All Terrain Defense Turret walkers. The ambush resulted in Calrissian and L3 losing the entirety of the cargo.
By the time between 2 BBY and 0 BBY, the Interdictor-class Star Destroyer, a variant of the Imperial-class Star Destroyer, was developed and in service to the Imperial Navy. One Interdictor Star Destroyer was commanded by Admiral Gable Karius above Mustafar, capturing the smuggling ship Windfall.
By 0 ABY, the Immobilizer 418 was no longer manufactured by the Empire due to its vulnerabilities, favoring to place the gravity well projectors on Star Destroyers instead as they were more difficult to destroy. Additionally, the Empire also cancelled production of the Interdictor-class heavy cruiser, as they proved an easy target for rebels and again favored to place the projectors within Star Destroyers. Despite this, Immobilizer 418 cruisers continued to be in service throughout the galaxy due to their abundance. One Immobilizer managed to pull Luke Skywalker out of hyperspace into the Daalang system after he managed to free a high-priority asset from the Imperial cause. However due to the ships frequent use against Alliance raiding groups, Luke Skywalker was able to form an attack strategy against the ship, ultimately destroying the vessel by splitting it in half with a Utheel Rockcrusher Compact Seismic Charge.
In 3 ABY, Hunter Fleet's secondary strike force utilized an Interdictor during a battle near Malastare against the Eighth Division of the Alliance Navy. Following the Syndicate War and other actions by Crimson Dawn, an Interdictor Star Destroyer was attacked by the Crimson Dawn flagship Vermillion. In 4 ABY, Interdictors formed the Imperial forces during the Battle of Endor. The Imperial ships hid behind Endor and moved into position to block an immediate escape while the fleet's Interdictors activated their generators to fully trap the Alliance fleet. Alliance starfighters outflanked the Imperial fleet and attacked the Interdictors and Imperial communications, and the DS-2 Death Star II Mobile Battle Station was eventually destroyed. As a result of the defeat, the surviving Imperial forces retreated.
In 5 ABY, the Interdictor-class cruiser Spectral participated in the Battle of Fondor Shipyards against the New Republic, and soon retreated to Jakku. In transit, one of its projectors was damaged by a Republic starfighter that managed to track the cruiser through hyperspace. Once in Jakku's orbit, the starfighter was brought in and the ship sabotaged, resulting in it crashing to Jakku's surface. Within moments, the New Republic Defense Fleet appeared and commenced the Battle of Jakku against the royalist Imperial forces, consisting of at least three naval battle groups. The Immobilizer Glaciate participated in the battle, during which it was infiltrated and captured by the New Republic operatives acting on General Carlist Rieekan's orders. The battle resulted in the end of the Galactic Civil War and the final collapse of the Galactic Empire. Many years later, scavengers from Niima Outpost sought to travel within the wreckage of the Spectral to plunder it.
The concept of the Galactic Empire disabling vessels' hyperspace capabilities using Interdictor vessels first appeared in the Star Wars: The Roleplaying Game 1989 supplement Imperial Sourcebook and later used in Heir to the Empire, a 1991 novel by Timothy Zahn that was the first in a trilogy featuring events set several years after the conclusion of the final film of the original trilogy. While this trilogy is now considered part of the franchise known as Star Wars Legends and no longer canon, Interdictor vessels were featured in novels such as Tarkin and Heir to the Jedi, which are considered part of a new continuity of canon.
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