For 50 years, a secret was kept by a US pilot who shot down four Soviet MiGs in just 30 minutes during the Vietnam War.

On Tuesday, the story of retired Air Force Lt. Col. Leo Thorsness was finally revealed. Thorsness was awarded the Medal of Honor for his actions in April 1967.

According to the US Air Force, Thorsness, flying an F-105 Thunderchief, was on a mission to strike an enemy surface-to-air missile site in North Vietnam when he encountered two MiG-17s. He managed to shoot down both of them, despite being heavily outnumbered.

Thorsness and his wingman then headed back to their base, but were intercepted by two more MiGs. In a daring move, Thorsness engaged the MiGs and shot down both of them.

The Air Force said Thorsness’ actions “saved the lives of his wingman and numerous strike aircraft.”

“My wingman and I were outnumbered and outgunned,” Thorsness said in a statement. “We had to do something to survive and hopefully turn the tables. I’m just glad we were able to do it.”

Thorsness’ story has now been revealed after 50 years of secrecy, and the Air Force has recognized him for his bravery and courage. He is the first Vietnam War pilot to receive the Medal of Honor.