The Third Battle of Theed was a battle that took place in 19 BBY between the Galactic Empire and the people of Theed, Naboo. It was used as a diversion so that Ferus Olin could find and kill Malorum, who had discovered the secret that Padmé Amidala gave birth before she died and her child was alive (he didn't know they were twins).
The Royal Naboo Security Force and Gungan Army attacked the Imperial garrison in the city. Meanwhile, Olin found Malorum, who revealed that he possessed a lightsaber, and engaged Olin in a duel. The duel was fought in the Theed Power Core, where Obi-Wan Kenobi and Qui-Gon Jinn had fought Darth Maul many years before.
Olin managed to overcome Malorum, who fell down a power core in a futile effort to reach his lightsaber which Olin had knocked from his hand. Afterward, the Theed Hangar, which was being used by the Empire to store illegal explosives, was destroyed by Olin to cover the destruction of the Imperial Garrison. Consequently, Naboo escaped serious punishment by the Empire, who did not wish to draw attention to the fact that they were breaking the law.