The seizure of the Zeplin occurred during a conflict known as the Zaarin uprising.
Following the attack on Emperor Palpatine's personal C-3 transport ship, the Excalibur, while it was heading towards Endor, the Victory-class Star Destroyer Zeplin, under the command of Namuura Din, managed to get away from the combat zone. Intelligence provided by an Imperial loyalist who was secretly working on the Zeplin indicated that Din and the Zeplin were priority targets. This was because they not only possessed a stolen Missile Boat which they planned to give to the Rebel Alliance as part of a defection, but also because Din was rumored to possess information regarding the actual operational condition of the second Death Star. Revealing this information would jeopardize the Emperor's trap at Endor. Therefore, Darth Vader was dispatched aboard his Imperial-class Star Destroyer Garrett to intercept the Zeplin. The Imperial Ace and Emperor's Hand Maarek Stele accompanied Vader, personally leading Tau Squadron, while Assault Gunboats of Mu Squadron engaged the Zeplin.
When Stele arrived at the Zeplin's location, he discovered that an MC80 Star Cruiser, named the Link, was already present, and the meeting was underway. Stele quickly scanned the Link and confirmed the presence of a stolen Missile Boat inside the cruiser. Soon after, a Delta-class DX-9 stormtrooper transport, designated Z-Epsilon 1, carrying officers, launched from the Link as it entered hyperspace. Stele destroyed the transport and swiftly dealt with the modified TIE fighters. The TIE Interceptors then engaged the Assault Gunboats, but Stele eliminated them. Subsequently, Stele fired advanced missiles at the Zeplin's warhead launchers and advanced torpedos until its shields collapsed, allowing the Gunboats to disable the Zeplin. While Stele was occupied with the TIE Avengers, the Imperial-class Star Destroyer Garrett arrived and launched an assault transport, Omega 1, to board and secure the Zeplin. As the boarding operation progressed, Rebel A-wings and B-wings entered the area, with the A-wings targeting the transport and the B-wings attacking the Garrett. However, the Garrett's own starfighters and Maarek Stele destroyed the Rebel attack.
The Zeplin was successfully seized and was scheduled to be sent to an Imperial shipyard for examination by Imperial Intelligence, while Din was taken into custody and interrogated by Darth Vader. The interrogation revealed two key pieces of information. Firstly, Grand Admiral Zaarin was fully aware of Palpatine's plans at Endor but only intended to inform his loyal forces, without any sympathy for the Rebels, which prompted Din's defection. Secondly, and more importantly, the Link had escaped with not only the Missile Boat prototype, Sealion, but also with knowledge of the true status of the Death Star II. Nevertheless, it was eventually located and captured by pursuing Imperial forces, including the Garrett.
This battle is featured in the 1994 PC game Star Wars: TIE Fighter as Battle 13 mission 2, entitled "Capture the turncoat." This article assumes that both Primary and Secondary objectives, and most, if not all, Bonus objectives, are completed.