When the Fire Nation invaded Omashu, earthbenders and soldiers, led under the command of Yung, prepared for battle. However, KingBumi, utilizing his fighting style of neutral jing, surrendered the city, which was subsequently occupied by the Fire Nation and renamed New Ozai. Though Bumi had been captured, the remaining citizens still organized a resistance. Yung and his soldiers quickly formed the underground resistance in the sewers with the objective of driving the Fire Nation out.
During the spring of 100 ASC, they pushed stones and rocks down the city's chutes toward the governor and his family, wishing to eliminate them, but AvatarAang blasted the rocks away with his airbending. Shortly afterward, with some persuasion by Aang, Yung agreed to evacuate all the citizens of Omashu in the hopes of fighting another day, using the false pretense of a plague. His wishes of freedom came true during the eclipse when King Bumi, in whom Yung had lost faith after the capture of Omashu, saw that it was the right time to strike and single-handedly liberated his city, turning the resistance movement into a success.