Star Wars: X-Wing Tour of Duty: Imperial Pursuit, which added new missions for players, was the initial expansion released for the Star Wars: X-Wing video game. This occurred in 1993, and later that same year, it was followed by the B-Wing expansion. Bundled releases of the original game would later include both of these expansions. After installation, the Imperial Pursuit missions were accessible in-game as "Tour of Duty IV".
As the Rebels evacuate Yavin 4 and search for a new, secure base location, they must withstand increasing pressure from the Imperial forces, including the new Interdictor Cruiser.
During the first part of the tour (missions 1–5), the Rebel Alliance evacuates Yavin and disperses to evade Imperial retaliation for the destruction of the Death Star. However, a significant portion of their crucial food supplies are lost during this initial evacuation.
In the second part (missions 6–14), the Rebels are struggling to obtain food. Ghorin, the Overlord of the Greater Plooriod Cluster, claims to sympathize with the Rebellion and offers them the desperately needed supplies. However, his offer is a deception, and he instead provides poisoned grain. To get revenge for this betrayal, the Rebels undermine Ghorin by first stealing some of his Y-wings (to use in attacks against Imperial food shipments) and then replacing his usual grain shipments to the Empire with the contaminated grain they received. Consequently, Darth Vader executes Ghorin.
In the concluding part of the campaign (missions 15–20), the Rebels steal TIE Advanced fighters (for study), destroy the frigate Red Wind, and begin preparations for Operation Ram's Head. This operation involves capturing the Corvette Blade 5, which is carrying the experimental Shield X technology. The Corvette is then utilized to attack and effectively destroy an Imperial deepdock by ramming the bridge towers of several Star Destroyers.
Players are awarded the Shield of Yavin medal for successfully completing the tour of duty.