In the year 3 BBY, the group known as the Spectres embarked on a mission targeting Lothal. Their objective was to infiltrate an Imperial depot located on the planet Lothal, with the intention of seizing three Sphyrna-class Hammerhead corvettes. These specific corvettes had been discreetly delivered to Lothal by Princess Leia Organa of Alderaan, who presented the delivery as a humanitarian aid mission, while the true intent was to provide the rebellion with vital resources. The rebel forces engaged in combat against an Imperial garrison led by Lieutenant Yogar Lyste. Lyste, under the impression that Organa was a loyal supporter of the Empire, was ultimately unsuccessful in preventing the theft of the vessels. Through the combined efforts of Leia and the former Lothalian Governor Ryder Azadi, the rebels successfully acquired the three corvettes, significantly strengthening Phoenix Cell.
Phoenix Cell had suffered considerable casualties during their escape from Imperial forces stationed on Garel. Upon learning about these losses, Alderaanian Senator Bail Organa, a clandestine supporter of the rebellion, dispatched his adopted daughter, Princess Leia Organa, with the purpose of supplying reinforcements to the Phoenix rebels. These reinforcements consisted of three Sphyrna-class Hammerhead corvettes: the Lightmaker, the Amity's Arrow, and the Duchess Senna, which were later designated as P1, P2, and P3. Due to the impossibility of the Alderaanians directly transferring the ships to the rebels without revealing their disloyalty to the Empire, Leia Organa orchestrated a plan to have the ships delivered to Lothal, an Imperial-controlled world, under the guise of delivering essential relief supplies. The rebels would then ostensibly "steal" the ships, thus shielding the Alderaanians from accusations of supporting the rebellion.
Under the pretense of providing relief supplies to the inhabitants of Lothal, who were enduring a lockdown due to the ongoing rebel insurgency, Princess Leia journeyed to the planet. Upon their arrival in Lothal's orbit, Lieutenant Yogar Lyste directed them to land at an Imperial depot situated near the town of Jalath. After landing, Leia was met by two members of the Spectres: Kanan Jarrus, a former Jedi Padawan, and his apprentice, Ezra Bridger. They were cleverly disguised as a stormtrooper and an Imperial cadet, respectively. Kanan and Ezra had received instructions from Hera Syndulla to meet with Leia to execute the "theft" of the starships.
Leia's plans encountered a significant obstacle when Lieutenant Lyste employed gravity locks on the corvettes to prevent any unauthorized removal. Lyste was aware of the history of Alderaanian ships being stolen on Imperial planets, but he lacked concrete evidence linking Leia to the rebellion. As an additional precaution, Lyste deployed two AT-AT walkers to guard the ships and instructed his stormtroopers to thoroughly search the vessels for any contraband. Without a dedicated transport for her supposed "relief work," Leia requested and received permission to use Lyste's Sentinel-class landing craft, and then departed with Kanan and Ezra. As they flew across Lothal's plains, they intercepted a distress signal from Chopper.
Upon arriving at Ryder Azadi's secret hideout, they discovered that stormtroopers had apprehended both the former Governor and Chopper. The Imperials had received orders to execute Azadi. Kanan, still in his stormtrooper disguise, and Leia attempted to reason with the Imperials, but their efforts were futile. Their discussion was interrupted by the arrival of the Spectres' ship, the Ghost. While Hera piloted the VCX-100 light freighter, Sabine Wren and Garazeb Orrelios launched an attack on the stormtroopers and successfully rescued Kanan, Ezra, Leia, and Ryder. During the conflict, Lyste's landing craft was destroyed when Chopper fired the Phantom's weapons at the shuttle. To conceal Leia's connections to the rebellion, Ryder feigned abducting her, while Zeb pretended to take Kanan and Ezra, still in their Imperial disguises, as prisoners when they attempted to "rescue" the princess.
After successfully evading the Imperials, the crew of the Ghost convened to strategize their plan for seizing the Hammerhead corvettes. Although Azadi was hesitant to fully commit to the rebellion, he ultimately agreed to assist in deactivating the gravity locks in exchange for guaranteed safe passage off Lothal. According to the plan, Leia, accompanied by Kanan and Ezra (still clad in their Imperial military uniforms), would travel to the Imperial depot aboard the Phantom. Sabine, Chopper, and Azadi would conceal themselves within the shuttle. While Leia and her companions diverted Lieutenant Lyste and his forces, the remaining rebels would disembark, disable the gravity locks, and liberate the impounded ships. Simultaneously, Hera and Zeb would engage the Imperial walkers using the Ghost.
As Leia engaged in conversation with Lieutenant Lyste, Ryder, along with Sabine and Chopper, successfully disabled the gravity lock on the Hammerhead corvette P1. Following the deactivation of the locks, Sabine assumed control of the ship's helm. Upon realizing that intruders were attempting to steal the corvette, Lyste commanded his troops to intercept the rebels. One of the AT-AT walkers attempted to shoot down the corvette. Meanwhile, Ryder and Chopper proceeded to disable the gravity lock securing the second Hammerhead corvette, P2, but were detected by Imperial stormtroopers. Sabine, piloting P1, opened fire on the Imperials. Kanan and Ezra incapacitated Lyste and two of his stormtroopers.
During the ensuing conflict, an AT-AT that had been temporarily disabled by the Ghost's proton torpedoes regained its footing, prompting Kanan to utilize his lightsaber to sever the walker's two right legs, causing it to collapse. After successfully disabling the second gravity lock, Ryder instructed Kanan to depart aboard P2. Ryder then attempted to board the third Hammerhead corvette, P3, but was cornered by two stormtroopers. Ezra then employed his Force powers to seize their blasters, and Leia grabbed one of the blasters and shot the troopers. In response to the escalating attacks, several Imperial Troop Transports arrived. Despite Leia's objections, the commander of the arriving stormtroopers ordered the remaining AT-AT walker to eliminate the remaining Hammerhead corvettes.
Aboard the third Hammerhead corvette, Ryder attempted to force the ship to fly despite the engaged gravity lock, engaging the thrusters and using the generated force to topple the second AT-AT. Having completed his mission, Chopper departed aboard the Phantom. Before their departure, Leia and Ezra exchanged farewells and promised to meet again. To maintain the illusion of her continued loyalty to the Empire, Leia instructed Ezra to stun her. Shortly thereafter, Leia was recovered by Lyste and his stormtroopers. Feigning outrage at the Imperials for the loss of her ships, Leia threatened to report their incompetence to the Imperial Senate. However, Lyste managed to appease Leia by offering to provide compensation for her missing ships. The Imperial officer then came to the realization that his own ship had also vanished; the Sentinel-class landing craft had been destroyed by the crew of the Ghost during the alleged "kidnapping" of Leia and the disguised Kanan and Ezra.
The raid conducted on the Imperial depot at Jalath proved to be a triumph for Phoenix Squadron, enabling them to recover from the losses they had incurred on Garel. Lieutenant Lyste was summoned to a meeting with high-ranking officers, where he received a reprimand for the theft. Meanwhile, in space, Ryder, now understanding that what Ezra's parents initiated had expanded beyond his expectations, pledged his support to the rebel cause, both for their sake and for their son's. Despite this modest victory, the rebellion remained significantly outmatched and outgunned by the Galactic Empire, which maintained control over a vast portion of the galaxy. P2 was eventually lost during the Battle of Atollon, while P1 and P3 joined the larger rebellion. One of these two ships, the Lightmaker, ultimately sacrificed itself in the Battle of Scarif to destroy two Star Destroyers and breach the Shield Gate.
At a later time after the mission, Organa filed a formal complaint with Moff Stattata of the Lothal sector. Following this complaint, the Empire provided compensation to the Royal House of Alderaan to reimburse them for the "stolen" ships and cargo. The total value of the claim amounted to 2,242,500 credits.
The Raid on the Lothal Depot served as the climax within the Star Wars Rebels episode entitled "A Princess on Lothal," which was initially broadcast on Disney XD on January 20, 2016. It featured the Original trilogy character Princess Leia (with her voice provided by Julie Dolan) as a special guest character.