Yon Rha became the commander of the Southern Raiders around 86 ASC. In 94 ASC, he was tasked by Fire LordAzulon to find and dispose of the final remaining waterbender in the Southern Water Tribe. He and his men executed a raid on the tribe during which Yon Rha interrogated Kya to find the last waterbender's whereabouts. Kya tricked him into believing that she was the one they were looking for in order to protect the real waterbender, her daughter, Katara. Yon Rha executed Kya on the spot, explaining that he did not intend on taking any prisoners.
Two years later, Yon Rha honorably retired, going home to live quietly with his ill-tempered mother in a peaceful Fire Nation village. Mostly due to the time he spent with her, he was reduced to a shadow of the proud commander he used to be.
Four years after his retirement, when he was returning home after grocery shopping, he was ambushed by Katara and Zuko, who had left the Western Air Temple to confront him, seeking vengeance for Kya's murder. He recognized Katara as the little Water Tribe girl he encountered during his last raid on the Southern Water Tribe when he killed the alleged last waterbender. However, he was proven wrong in his believe when Katara revealed that her mother had lied to protect the true last waterbender: herself. Seeing the pain and rage displayed in Katara's bending, Yon Rha cowered back from her fierce attack, raising his arms to protect himself from the icicles she shot in his direction to end his life. However, she halted her attack at the last moment, deciding to spare him.
He begged for his life, even offering the life of his own mother to even the score, though Katara refrained from executing her revenge, proclaiming that as much as she hated him, she could not bring herself to kill such a miserable target. Yon Rha was left crying and cowering in the dirt of the road.
Yon Rha was a very capable commander during his time in the Southern Raiders, effectively using his men in a frontal assault against the Southern Water Tribe as a diversion to allow him to enter into the settlement undetected. He was also a skilled firebender, able to react to a perceived threat within a short time. Yon Rha was also very alert, as even four years after his retirement, he was still able to perceive his surroundings, knowing full well someone had been trailing him from the market place on his way home.