Secret Letters and Invisible Ink: How Women Prisoners Revealed Abuses Inside Concentration Camp

Jhemmylrut Teng
Letters that were written in Urine(Source: Reuters)

At the height of the Holocaust, millions were being murdered in several concentration camps in Nazi-occupied Europe. The Nazis’ horrific treatment of the prisoners went far beyond inhumane when they used inmates as specimens for their scientific experiments.

In Ravensbrück, the only concentration camp for females, four young women were exposed to diabolical procedures carried out by the Nazis’ scientists while they were imprisoned.

It was a very well-kept secret then, but these women found an innovative method to send their messages to their families and the rest of the world: using their urine.

Ravensbrück women’s concentration camp

Ravensbrück was the Nazis’ concentration camp exclusive for women from 1939 to 1945, and it was located near Berlin, Germany. According to the Holocaust Encyclopedia, most of the women internees in this camp were Polish and were jailed as political prisoners.

In 1942, the German SS (Schutzstaffel) opened brothels in some concentration camps. They exploited female prisoners from Ravensbrück camp to become sex workers for male inmates. Forced prostitution served as a reward for male prisoners whenever they finished or exceeded their production quota.

Some women were compelled to become sex slaves, while others “volunteered” after the camp authorities promised them preferential treatment or release from the concentration camp after six months. None of the women were released as promised.

Women prisoners as a specimen

In 1942, under the supervision of Karl Gebhardt, the personal doctor to SS leader Heinrich Himmler. Nazi doctors began dragging inmates into their laboratories to conduct sick medical experiments, calling their victims “rabbits.”

These tests included treating wounds with various chemical substances to prevent infections. They also tested multiple methods of setting and transplanting bones, such experiments included amputations.

There were eighty women subjected to the Nazis’ physicians’ horrific experiments, mostly Polish inmates. Many of them died in the process, but those who survived suffered permanent physical and mental damages. However, at that time, such inhumane practices were unknown and contained to the walls of Ravensbrück.

In the midst of the unethical medical examinations in Ravensbrück, four Polish women were determined to expose the camp's abusive practices to female prisoners. They were Krystyna Czyz, Wanda Wijtasik, Janina Iwaska, and her sister Krystyna Iwaska.

At that time, due to the physical disabilities, they suffered during the tests, escaping the camp was impossible. Therefore, they decided to report on the experiments to the Polish resistance, believing it would soon reach the Polish government in exile, the International Red Cross, and foreign governments.

However, the problem was, how to make that feasible? How could they make their reports reach the outside of the camp?

Back then, the inmates’ only communication method with the outside world was through a letter each inmate was allowed to write to her family once a month. However, everything should be written in German. Besides this, the letter’s contents should be limited to a report on their “supposedly good condition” because each letter was subjected to SS censorship.

Anyone who differed from the stringent rules risked death.

Urine letter: hidden codes and messages

The very next day, the four wrote to their families. When Krystyna’s father received her letter, they found the message very odd, especially when she mentioned out of nowhere this phrase: “Satan from the Seventh Grade.

Krystyna’s brother was perplexed because why on Earth had she mentioned a children’s book. Then, her brother recalled the book’s plot. The book was about a seventh-grader who was smart, resourceful, and known for his sharp intelligence and detective skills.

While the child was investigating a mystery, he was caught by criminals and imprisoned in a cellar. To ensure that his disappearance did not arouse suspicion, they demanded that he wrote a letter to an adult friend. He wrote to his professor, saying that he’d gone on a trip for a few days. But his note was very cryptic until the professor figured out the message, it was a warning: “Safeguard the house.”

Because of this book, Krystyna’s brother recognized that she might do the same thing. The Czyz family worked it out until they figured the hidden code, it said, “letter in moczem,” which means “letter in urine.”

Urine loses its color quickly when in contact with the paper, it becomes invisible. However, if the paper is heated, the writing reappears. So, Krystyna’s mother applied a hot iron to these letters, and the secret message was revealed.

The hidden message

Krystyna wrote in the margins of the letter using a thin stick dipped in her urine. She narrated the medical experiments to which she and her friends had been subjected and signed off by noting that her family should expect more letters in the future.

The four inmates continued sending letters using their urine as invisible ink. They used different methods, filling every empty space in the paper, and even the envelope. To write longer messages, they divided the texts and asked their families then to meet secretly together to piece all the texts like a puzzle.

The information was all about the camp’s atrocities, particularly about the medical experiments that had mostly gone wrong. They also reported the demise of several young women while these tests were being executed.

These four women provided first-hand statements about Nazi crimes against humanity inside the camps Ravensbrück.

The medical exposé

In May 1944, after a year of transmitting coded messages to their families. A radio station in England aired the contents of their letters.

“In the concentration camp for women in Ravensbrück (…) the Germans are committing new crimes. The women in this camp are being submitted to vivisection experiments and are being operated on like rabbits. The [occupation] authorities have made lists of all women who had to submit to such operations. It is feared that these records are being kept for the purpose of murdering these women so as to obliterate all traces of their crimes… At present, there are close to 3,000 Polish women in the Ravensbrück camp.”

The broadcast continued with a warning to the Nazi authorities that their days were numbered, and they will pay for all the injustice they had committed to all the women of Ravensbrück.
Letters that were written in Urine(Source: Reuters)

Justice after the war

In 1945, the Nazis started evacuating prisoners out of Ravensbrück, and many of these women were forced into the death march. By April of that same year, the Red Army captured the camp and finally freed the remaining prisoners.
Dr. Karl Gebhardt's trial in post-WW2(Source: Washington University Library)

Guards and wardens were captured and tried between 1946 to 1948. Karl Gebhardt, the doctor who guided the camp experiments, was sentenced to death during the Nuremberg Doctors’ Trial. In all cases, the secret messages sent by the four young women of Ravensbrück were used as evidence against the torturers.

The four young Polish women who courageously exposed the Nazi's inhumane medical experiments survived the persecution of the Holocaust during the Second World War.

Krystyna received a scholarship from the University of Lublin, she pursued a degree in geography and became an academic. Wanda became a psychiatrist, Janina became a journalist, and her younger sister Krystyna became a doctor.

After several decades, Krystyna Czyz-Wilgat’s daughter found twenty-seven letters stuffed in the furniture in their home. Those were the iconic urine letters her mom wrote while in Ravensbrück.

In 2017, they donated the letters to the Martyrdom Museum “Under the Clock” in Lublin, in eastern Poland.

“Even though there were broad reports about the Auschwitz camp, on Ravensbrück there was little information released. And only those female Poles were the ones who conveyed this information. That is why these letters are such a valuable material and historic evidence,” — Barbara Oratowska, Curator of the Martyrdom Museum “Under the Clock”
Letters that were written using prisoners' urine is now displayed in Polish Museum(Source: Reuters)

What these four Polish women had gone through inside the Ravensbrück prison was beyond daunting. However, fear didn’t stop them from speaking up and fighting for all the women’s freedom, rights, and justice inside the Nazis’ death camp. Their resourcefulness, creativity, and sheer audacity led to the Nazi doctors’ persecution after the war.

At a time when these women needed a hero to save them, they ultimately became one.

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I am a PR officer and a professional journalist with a master's degree in international development. I write history, geopolitics, food, and culture. Since I am a member of the API community, I make sure to highlight our stories to promote diversity and create awareness for cultural understanding.


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