Stephanie Czech Rader was the daughter of Polish immigrants, uneducated laborers who settled in Poughkeepsie, N.Y., in the early 1920s and barely spoke English. Her immersion in Polish language and culture proved critical to her success, against daunting odds, as a U.S. spy in Europe after World War II.

Recruited to the Office of Strategic Services and the Strategic Services Unit of the War Department, precursors to the CIA, she was officially employed as a clerk at the U.S. Embassy. In reality, she was undercover, an agent whose flawless Polish accent and mannerisms allowed her to move around the Soviet-dominated country with relative ease.

She faced near-constant hazard anyway. Conditions in Warsaw were bleak and dangerous. Pro-Soviet factions surveilled the movements of embassy personnel. Ultimately, she had her cover blown in what was tantalizingly if only passingly alluded to in official paperwork as an act of “gross negligence” by a superior based in Paris.

Despite these impediments, she was able to document vital information on Soviet troop movements and other invaluable details at the pre-dawn of the Cold War.

At the time of Mrs. Rader’s death on Jan. 21 at 100, a campaign was underway by members of the OSS Society, a group preserving the spy agency’s legacy, to obtain the Legion of Merit on her behalf. The award — honoring “exceptionally meritorious” service — had been denied her for unknown reasons in 1946.

Stephanie Czech Rader in the 1940s. (U.S. Army via Cornell University)

“Like many of those who served so heroically in the OSS,” said OSS Society President Charles Pinck, “she was never properly recognized for her heroism. When the OSS personnel records were declassified in 2008, we learned that she had been nominated for the Legion of Merit. She never received it. I hope the Army will award it to her posthumously.”

Stephanie Czech was born in Toledo on May 16, 1915, and grew up in an immigrant neighborhood of Poughkeepsie. Her early experience in public school, where other children spoke English, was challenging.

“When you get to school and everyone is speaking something different,” she told an interviewer years later, “for survival you have to learn in a hurry.”

She began to show academic promise, and a teacher took an interest in her welfare. Without her knowledge, her mentor, a female graduate of Cornell University, submitted an application on her behalf to the Ivy League college.

According to a Cornell alumni publication, she won a full scholarship and waited tables before receiving a bachelor’s degree in chemistry in 1937. Because of the Depression, and likely her sex, she struggled to find work in her field. She eventually became a translator of scientific studies for the Texaco oil company in New York.

After the United States entered World War II, she left civilian life to join the new Women’s Army Auxiliary Corps in 1942 and was groomed as an officer. Her Ivy League education and Polish language skills attracted the attention of the OSS in December 1944.

She arrived in Warsaw in October 1945, one of only two OSS representatives in the country. In addition, women generally were prohibited from working in a military or intelligence capacity in Poland at the time — the capital was reduced to rubble by the war, and the risk of assault was high.

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Although Cold War hostilities had not officially begun, anyone who aroused the suspicions of the Soviets or pro-Soviet Polish authorities risked being shot or disappearing. A Naval attache assigned to the U.S. Embassy vanished while on assignment in southern Poland and was never heard from again.

But the ambassador reputedly made an exception because of her skills and gave approval for her undercover assignment.

She accepted the terms of espionage duty in Poland. They included wearing civilian clothes, which would have left her without the protection afforded those in uniform if she were ever taken into Soviet or Polish custody.

Capt. Czech, as she was then known, traveled often unaccompanied far from Warsaw under the pretense of seeking news of family members in the aftermath of the war. Sometimes those relatives surfaced, and during extended stays with them, she was credited in official documents with reporting back “considerable” intelligence on Soviet troop movements, the activities of the Soviet and Polish security forces, and economic and political data that could not otherwise be obtained by American embassy officials.

She was also put to work as a courier between Berlin and Warsaw and was almost captured when returning to Warsaw on Jan. 15, 1946, with top-secret documents intended for embassy personnel. As she approached the German-Polish border checkpoint on foot, she gingerly slipped the package of materials to a less suspicious traveler and instructed the person to take the files to a safe address in Warsaw.

Although singled out by border authorities, the supposed embassy clerk managed to avoid immediate detention but endured intensified surveillance. According to the Legion of Merit recommendation at the time, her embassy cover had been compromised by a superior in Paris. She nonetheless volunteered to remain in Poland several more weeks to fulfill her mission.

In the ensuing months, she was nominated for the Legion of Merit — a decoration honoring “exceptionally meritorious” service. That recognition and a lower award, the Bronze Star Medal, which described her “unusual fortitude and sang-froid,” were denied. No cause was given.

She later was elevated to the rank of major before soon leaving the Army. Her decorations included the Army Commendation Ribbon, later known as the Army Commendation Medal.

After the war, she married William S. Rader, an aircraft commander who had carried out bombing raids during the Battle of Midway in the Pacific and later deep penetration sorties over targets in Europe.

Mrs. Rader received a master’s degree in chemistry from George Washington University in 1951 and later accompanied her husband on his Air Force assignments. He retired at the rank of brigadier general and died in 2003 after 57 years of marriage. They had no children, and she had no immediate survivors.

Mrs. Rader died at her home in Alexandria. She had Parkinson’s disease, but the immediate cause was complications from recent surgery, said a friend, Michael Golden.

After decades of silence about her exploits, Mrs. Rader was feted in 2012 by the OSS Society and was the inaugural recipient of its Virginia Hall Award, named after the intrepid, one-legged spy who helped Resistance fighters in Europe.

Mrs. Rader did not embody the cliches of Hollywood espionage. She was a chemistry major who glided into the shadows, hardened to spycraft but only up to a point.

“They gave me a gun but I never carried a gun,” she said. “What the heck was I gonna do with a dumb gun?”