Via Starwars.com:

THE EVOLUTION OF THE REBEL FLEET SIGNIFIED CHANGES IN ITS ONGOING CONFLICT WITH THE EMPIRE.

The struggle between the Rebel Alliance and the Galactic Empire in the original Star Wars trilogy was a brutal conflict that took place on distant worlds and in the darkness of space. The scenes of interstellar warfare involving the vessels of the Rebel Alliance were memorable, but the type and strength of the Rebel forces in each engagement also paralleled the developments in the trilogy’s plot pertaining to the Rebellion’s progress towards success.

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