They were called "back-enders" - men who toiled in anonymity in the cramped rear of spy planes intercepting radio signals high above enemy territory.
Two such men, Staff Sgt. Donald G. Hill and Airman 2nd Class Earl W. Radlein Jr., were remembered in a ceremony yesterday at the National Security Agency, a half-century after Soviet fighter jets shot them out of the sky at the close of the Korean War.
"Their service and sacrifice stand as testament to the idea that the successful practice of cryptology is not always conducted in safe, secure surroundings," agency officials wrote in the program for the closed ceremony at NSA's Fort Meade headquarters.
The names of Hill and Radlein are etched into a black granite memorial built six years ago to honor codebreakers who have died in the line of duty.
The 12-foot memorial stands inside the NSA's main building. Like most everything else at the clandestine eavesdropping agency, it is closed to the public.
But the NSA has sought in recent years to cast at least a sliver of light on its role in the country's history, and last year it began telling the stories of the 152 codebreakers who have died on the job since the agency's founding in 1952.
The stories of Hill and Radlein were made public after yesterday's ceremony, in a two-page NSA report headed, "They Served in Silence: The Story of Cryptologic Heroes."
It was a July morning in 1953 when the two young men stepped aboard a reconfigured B-29 bomber at the Yokota Air Force Base in Japan.
Hill, 29, a World War II veteran from Washington state, was an Air Force linguist who had flown countless reconnaissance missions. Sitting beside him that day was Radlein, 22, a brainy Tennessee native who had dreamed of flying planes but, like Hill, wound up in the newly formed Air Force Security Service.
An armistice in the Korean War had been reached two days earlier. But the Cold War was just beginning, and Washington wanted an unbroken stream of intelligence on the Soviet Union's military capabilities.
So the B-29, part of the 91st Strategic Reconnaissance Squadron, roared into the sky over the Korean Peninsula and went to work.
The crew completed its mission, and the pilot banked south toward the base in Japan. By then, however, Soviet MIG fighter jets had caught up with the slower B-29 and opened fire.
The shot-up plane plunged toward the Sea of Japan. Sixteen of the 17 crewmembers ejected. Just one, the co-pilot, survived.
Yesterday's ceremony drew 13 members of Radlein's family, who had traveled from North Carolina and posed for pictures with NSA director Lt. Gen. Michael V. Hayden.
The NSA was unable to locate Hill's family.