In the year 0 BBY, Perry, a Platypus operative working for the Alliance to Restore the Republic, gained unauthorized access to a specially modified Star Destroyer belonging to the Galactic Empire and successfully acquired the blueprints for their Death Star superweapon.
The operation to procure the Death Star blueprints was depicted in Phineas and Ferb: Star Wars, a special, non-canon crossover episode with the Disney Channel program Phineas and Ferb. This special was first broadcast on July 26, 2014.
Within the established Star Wars narrative, the endeavor to secure the Death Star blueprints occurred before the Battle of Scarif, which served as the culminating conflict in the Star Wars Anthology movie Rogue One: A Star Wars Story, which premiered on December 16, 2016. Similarly to the mission portrayed in the special, the Rebel Alliance successfully obtained the Death Star plans during the Battle of Scarif. However, in contrast to the special, where the mission involved a space battle, Rogue One features a battle that unfolded on the ground of Scarif.