When the top of the message said “for the president’s eyes only,” Rex Yocum left his typing and moved to another encryptor chair, finishing the secret information. He gave it to a courier with a briefcase handcuffed to his wrist under the watchful eye of a higher-ranking officer.
The Pentagon took few risks with spies, and Yocum was a technician for the Signal Corps in the War Department Code Center. He was a different kind of solider in the war, working mostly in the U.S. and spending long days in an office building.
The Army drafted Yocum in 1942, the summer before his senior year at Chadron State College in Nebraska. He’d tried enlisting in the Air Corps but was color blind. In the Army, officials tested his typing skills and found he could type 80 words a minute.
He became a radio operator and soon after went to specialist training in cryptography. By December, he was in Washington, D.C., working in the Code Center.
Messages came in about everything from numbers of jeeps in the Normandy invasion to routine Red Cross notices when someone was sick.
“The thing with the invasions, I would hate to be the one responsible for that. You were dealing with people’s lives,” Yocum said.
“We were normally dealing with secrets, which were better with me.”
He would rather not know what the message said. He would decode or encode, pass it along and move on to the next task.
The encryptors were not allowed to talk about their work. Yocum sometimes wanted to tell his wife, Bonnie, but he didn’t dare. Encryptors couldn’t even talk to each other, and in fact rarely acknowledged they knew any of their co-workers outside of the office. On the bus in the morning, none said “hello” or offered casual greetings. The laws were serious, war was serious, and their punishment for disobeying, even in a seemingly innocent way, was serious.
“Every once in a while someone would pop up and talk about a message they received on a bus going into Washington,” he said.
“The next day, they were shipped out somewhere and they joined the ranks.”
For a serious breach in security, the offender went to jail.
He was trained on, and worked mostly with, a code machine called SIGABA, similar to the Germans’ ENIGMA.
On the machine, 10 rotors, rotating disks that replaced letters for a code, sat in a basket hooked together. The encoder had a keyboard, and every day there was a different setting.
Yocum still doesn’t completely understand how it worked — it wasn’t his job. Mathematicians created the codes, and technicians fixed anything that went wrong.
Most of the officers working with Yocum worked hard and were knowledgeable and fair, he said.
But there was one full colonel sent in to inspect their office who was less so. He wore old Cavalry pants, black boots, a flat hat and carried a riding crop. Each time he came to their offices, he complained about a clutter of papers on the floor or desks out of line. Everyone stopped working to clean. Finally, another colonel told him the mess happened because their jobs were done so quickly.
The full colonel never returned, but his revenge was to make the men do obstacle training in the Marine Corps. Each signal corps man received combat gear and completed the watered-down obstacle course.
“They said they were shooting live ammunition. I don’t know if they were, but we started calling ourselves the Pentagon Commandos,” Yocum said.
Shortly before the planned Japan invasion, officers sent Yocum to the Philippines to test a new code machine called the SIGNAN. It was more compact than the SIGABA and had a built-in bomb that could self-destruct if it landed in the wrong hands.
Security regulations said they couldn’t fly over enemy waters with the machine, so they joined a troop ship out of San Francisco.
Just as they pulled out of the harbor in August 1945, the war ended. The ship continued and Yocum completed his mission, testing and then destroying the new code machine.
When he returned, he received a message from the signal corps, a souvenir of sorts from his time spent transmitting secrets. He still has it today, a small brown paper with faded typewriter ink. It reads:
THIS IS THE FIRST MESSAGE IN HISTORY TO PASS BETWEEN JAPAN AND THE UNITED STATES OVER AN ARMY CIRCUIT.
IT IS THE FIRST DIRECT MESSAGE OF ANY KIND BETWEEN JAPAN AND THE UNITED STATES SINCE THAT INFAMOUS DECEMBER DAY IN 1941.
FROM THE UNITED STATES ARMY SIGNAL CORPS PERSONNEL OPERATING FROM SPECIAL FACILITIES ON A UNITED STATES NAVAL VESSEL IN THE WATERS OF TOKYO BAY COME FELICITATIONS TO OUR COMRADES IN ARMS.