SEOUL, South Korea — HONG YOON-HEE had an extraordinary tale to tell, to anyone who would listen, about how he risked his life trying to save South Korea during a pivotal moment in the Korean War but was then condemned to death and had to flee to the United States.

His plan, he said, was to clear his name.

Last year, after years of scouring military archives in the United States and South Korea and filing petitions and lawsuits, Mr. Hong achieved that goal. In February, a court in Seoul overturned his 1950 conviction of treason for fighting for North Korea.

Mr. Hong, 83, said in an interview that his quest was only half over, however. Now, he wants to be recognized as a hero.

“For 63 years, I lived with the stigma of being a traitor,” said Mr. Hong, who lives in California but remains a South Korean citizen and has visited Seoul frequently. “The truth is I helped save South Korea during one of its most critical times.”