The Constrainer, a heavy cruiser of the Interdictor-class, saw action with the Imperial Navy during the Galactic Civil War. Its gravity well projectors enabled it to generate an interdiction field, which is essentially an artificial gravity well. This field allowed the Interdictor to stop other vessels from jumping to hyperspace. During the campaign against the rebel Phoenix Cell, this heavy cruiser was assigned to the 7th Fleet under the command of Grand Admiral Thrawn. In 2 BBY, the Constrainer was part of an Imperial squadron dispatched to the planet Atollon, where the Phoenix Cell had established their base.
During Thrawn's subsequent assault on the rebels, the Constrainer, along with another Interdictor cruiser, played a crucial role in preventing enemy ships from circumventing the Imperial blockade. However, the other Interdictor met its end, which created an opportunity for rebel Lieutenant Commander Ezra Bridger to make his escape. Following this, Bridger recruited several Mandalorian warriors to support the rebels. These warriors, under the leadership of Bridger and Sabine Wren, boarded the hull of the Constrainer and targeted one of its gravity well projectors with their weapons. Despite facing resistance from Imperial jet troopers, the strike team succeeded in damaging the generator. This damage led to a catastrophic explosion that destroyed the ship, enabling the rebels to flee.
The Constrainer, a cruiser, was an _Interdictor-class heavy cruiser belonging to the Interdictor line's design. This vessel measured 1,129 meters in length and was equipped with various systems, including deflector shields, laser cannons, five sublight engines, and a hyperdrive. Its dorsal hull featured an open bay, with an enclosed hangar situated on the aft wall. As an Interdictor vessel, the Constrainer was armed with four gravity well projectors, which were capable of generating an interdiction field. This artificial [gravity well](/article/gravity_well] allowed the cruiser to forcibly remove other starships from hyperspace.
During the Galactic Civil War, the Constrainer was a part of the Imperial Navy, specifically assigned to Grand Admiral Thrawn's 7th Fleet during his campaign against the Phoenix Cell of the Rebel Alliance. In 2 BBY, Grand Admiral Thrawn discovered that the Phoenix Cell's headquarters, Chopper Base, was located on the planet Atollon in the Lothal sector. Subsequently, he instructed Admiral Kassius Konstantine to deploy an Imperial squadron to engage the rebels at Atollon. This squadron consisted of five Imperial-class Star Destroyers, with the Dark Omen serving as the lead destroyer; two Interdictor-class heavy cruisers, including the Constrainer and another under Admiral Konstantine's command; and two Arquitens-class command cruisers.
The squadron emerged from hyperspace in the Atollon system in a line formation, with the Constrainer positioned on the left. The Imperial forces immediately moved to disrupt the rebels' long-range communications. General Jan Dodonna, whose forces were assisting the Phoenix Cell, ordered all rebel ships to retreat, and an EF76 Nebulon-B escort frigate attempted to jump to hyperspace. However, the frigate was pulled back into realspace by the interdiction field generated by the Constrainer and the other Interdictor. Upon realizing that the Empire had deployed Interdictor vessels, Commander Jun Sato of the rebels recognized that the rebel fleet was trapped. Konstantine's heavy cruiser then opened fire on the Nebulon-B, at which time Imperial forces were reinforced by Grand Admiral Thrawn aboard his flagship, the Imperial I-class Star Destroyer Chimaera.
The rebels then initiated an attack on the Imperial blockade, with Commander Sato employing Danaan tactics. Thrawn ordered the Imperial vessels to maintain their positions and await the enemy's advance, which led to the rebels being overwhelmed. During this engagement, the Constrainer fired several laser blasts at the rebels. However, Commander Sato successfully lured Konstantine's heavy cruiser out of formation and then maneuvered the Quasar Fire-class cruiser-carrier Phoenix Nest to ram the Interdictor, resulting in the destruction of both ships. This action allowed Lieutenant Commander Ezra Bridger to escape to hyperspace in his Gauntlet starfighter, Nightbrother.
Following the destruction of the other Interdictor and Bridger's escape, the Imperial forces intensified their assault. The Constrainer repositioned itself perpendicular to the Imperial line, exposing its port side to the rebels. Ultimately, the rebels were compelled to retreat to their base on Atollon's surface. Thrawn's blockade then reorganized into a triangular formation, with a single Imperial-class Star Destroyer leading the group, followed by two more behind it, and the final three bringing up the rear. The Constrainer was positioned after this sextet, directly behind the Chimaera. From this location, the blockade began an orbital bombardment on Chopper Base, which was countered by the rebels' deflector shield generator.
In the meantime, Bridger journeyed to the Mandalore sector planet Krownest to enlist the aid of Mandalorian rebel Sabine Wren and her clan. At the Wren Stronghold, Bridger presented the family with a hologram depicting the Imperial blockade, including the Constrainer. Wren identified the Interdictor as the primary obstacle facing the rebels. After agreeing to assist, she requested that the astromech droid C1-10P retrieve schematics of the Constrainer to facilitate their attack planning.
While Thrawn initiated a ground assault on the rebel base, Bridger returned in the Nightbrother, supported by five Fang-class starfighters piloted by Mandalorian warriors. As the Fang fighters engaged the Imperial TIE fighters, the Nightbrother deployed Bridger, Wren, and four other Mandalorian warriors onto the hull of the Constrainer, where they prepared to attack its gravity well projectors. Aboard the Chimaera, Governor Arihnda Pryce was informed of the rebel boarding by an Imperial technician, and the governor ordered that the strike team be repelled.
The rebels had already begun firing on the aft starboard gravity well projectors, located on the dorsal side of the ship, using their blasters, even though the Constrainer's deflector shields were active. At that moment, six Imperial jet troopers flew over the generator and engaged the group. The rebels killed several of the troopers and continued their assault on the heavy cruiser, causing the hull to crack and emit lightning. Captain Hera Syndulla contacted Bridger and reported that the remaining rebel forces were heading towards the blockade. Two TIE fighters then targeted Bridger on the Constrainer, but they were quickly shot down by the Fang fighters. One of the Imperial starfighters crashed into the hull of the Constrainer and exploded. Bridger's group intensified their attack, with the Mandalorians using their jetpack-mounted rockets to further damage the gravity well projector.
The rebel attack caused the Constrainer's deflector shields to fail. The damaged gravity well projector then exploded, which allowed the rebels to return to the Nightbrother. The explosion spread across the Interdictor's hull, releasing smoke and lighting, and the heavy cruiser began to disintegrate. The Constrainer was then destroyed as it was consumed by blue flame, creating a shockwave. As the still-exploding wreckage slowly drifted towards Atollon, the remaining rebel forces flew over the burning vessel and jumped to hyperspace without impediment.
In 35 ABY, the historian Beaumont Kin mentioned in his book The Rise and Fall of the Galactic Empire that Thrawn understood the importance of forcing the rebels to remain engaged in battle. Kin then stated that Thrawn's strategy of trapping the rebel fleet with Interdictor cruisers at the Battle of Atollon perfectly exemplified the Grand Admiral's ability to anticipate and counter his enemies' strategies.
Within the current Star Wars canon, the Constrainer was first seen in the midseason trailer for the third season of the animated television series Star Wars Rebels, which was uploaded to the official Star Wars YouTube channel on January 4, 2017. The vessel then appeared in "Zero Hour," the season's final episode. The episode was released in two parts on March 25, 2017, as the twenty-first and twenty-second episodes of the season.
Notably, the Constrainer is absent from wide shots of the Imperial blockade in "Zero Hour", as seen here and here. In the corresponding episode of the Star Wars YouTube channel's Rebels Recon series, Rebels's animation supervisor, Keith Kellogg, explained that technical limitations prevented all of the ships from being rendered simultaneously.
Although the Constrainer was not named in the episode, it was identified in a preview for the reference book Star Wars: Battles that Changed the Galaxy, which was published on StarWars.com on June 17, 2021. The book itself was released on October 28 of the same year. The book incorrectly used an image of another Interdictor-class heavy cruiser, the Interdictor, from the Star Wars Rebels episode "Stealth Strike" to represent the Constrainer.
The name Constrainer originated in the Star Wars Legends continuity, where the vessel was an Immobilizer 418 cruiser used by Thrawn's fleet. It first appeared in Dark Force Rising, the second novel of Star Wars: The Thrawn Trilogy, which was written by Timothy Zahn and released in 1992. The first issue of the novel's comic adaptation then provided the ship's first visual representation. The comic was written by Mike Baron, illustrated by Terry Dodson, and published by Dark Horse Comics on May 28, 1997.