Mission to rescue C-3PO
The undertaking to liberate C-3PO, also known as the C-3PO liberation, transpired amidst the Galactic Civil War. R2-D2, a rebel astromech droid, embarked on this solo endeavor, piloting a T-65B X-wing starfighter to free his companion, C-3PO, a protocol droid, from the clutches of the Galactic Empire.
Prelude
During the conflict known as the siege on Tureen VII, C-3PO was captured by the notorious SCAR Squadron. When Luke Skywalker, Leia Organa, Han Solo, and R2-D2 returned to the rebel fleet, they opted against launching a rescue operation, considering SCAR Squadron too formidable. However, R2-D2, undeterred, resolved to execute a rescue mission independently.
The rescue
Upon R2's arrival at the Star Destroyer where C-3PO was imprisoned, he deactivated his X-wing, feigning death. After being retrieved by the Star Destroyer's crew, R2 neutralized an inspection team. Progressing towards C-3PO's location, R2 instigated widespread chaos aboard the ship. Finally reaching his friend's holding cell, R2 freed him, and together they made their way back to the X-wing and successfully escaped.
Aftermath
As the droids fled, Darth Vader pursued them relentlessly in his ship. Fortunately, Skywalker, accompanied by the Millennium Falcon and the Volt Cobra, intervened, and the group escaped into hyperspace.