Operation Sieve was one of the small operations that were led by Dark Lord of the Sith Darth Vader against the increasing activity of the Alliance to Restore the Republic, in 1 ABY. After the Battle of Yavin, during the Galactic Civil War, the Galactic Empire and the Rebel Alliance struggled for the control of several cities in the galaxy. During periods of Imperial occupation of the cities of Bestine, Coronet City or Theed, Darth Vader landed in these three capital cities aboard his shuttle ST 321. Accompanied by a group of Triumphant-class dark troopers, the Sith Lord attempted to rally support for the Imperial cause and recruit troops for dangerous missions against the Rebellion. Vader recruited a group of skillful spacers affiliated with the Galactic Empire to hunt down military forces of the Rebellion. The spacers subsequently traveled in the galaxy and killed twenty-five Rebel guardsmen in Alliance-controlled cities. The successful Imperial spacers were later assigned to Operation Lumberjack.
Operation Sieve appeared as a quest in the 2003 video game Star Wars Galaxies, a massively multiplayer online roleplaying game developed by Sony Online Entertainment and published by LucasArts, prior to its closure on December 15, 2011. The quest was added to the game with the "Publish 19," on June 29, 2005.
During periods of Imperial occupation of the cities of Bestine, Coronet or Theed, Darth Vader would periodically land in these cities. Vader would offer players of the Imperial faction up to eight different quests, half of which were designated as "Combatant" quests (to be carried out against Rebel non-player characters), and the other half of which were designated as "Special Forces" quests (to be carried out against Rebel-aligned players). Operation Sieve was the second of the four Imperial Combatant missions that players received from Darth Vader. The player had to kill 25 rebel NPCs named "a watchful Rebel guard" and received 25,000 credits and 500 imperial faction points as reward.