My Great-Grandfather Made Chemical Weapons for the Nazis

June 28, 2026

AI Summary

5 min read

In a Berlin parliament building in 2021, writer Joe Dunthorne stood before an audience that included members of the far-right Alternative for Germany party. He had been invited to speak about his grandmother, a German Jewish refugee, as part of an exhibition celebrating Jewish lives before and during the Nazi period. But Dunthorne had recently discovered that his great-grandfather, Siegfried Merzbacher, was not simply a Jewish chemist who fled persecution—he was a man who developed chemical weapons for the Nazis, improved mustard gas, and helped facilitate a sale of poison gas to Turkey that was used in a genocide. Standing at the podium, Dunthorne made a decision: he would not mention any of that. He would stick to the safe, clean version of the family story. "I ended up doing a Siegfried," he says—editing the truth to avoid discomfort, just as his great-grandfather had done in his own 2,000-page memoir.

The Confession Hidden in 2,000 Pages

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What you'll learn

1 (02:15) **Episode Introduction & James Baldwin's "Trapped History"** - Hosts Oswin Baker and Carla Ray Shawnessy introduce the show's core concept, explaining James Baldwin's quote about people being trapped in history and history being trapped in them.
2 (05:37) **Joe Dunthorne's Path to Family History** - Joe explains how he, the son of two historians, initially resisted writing about history, and how his family questioned whether he was ready for the task.
3 (09:39) **The Family's Romantic Origin Story: Radioactive Toothpaste** - The episode introduces the family's cherished tale of Siegfried Mertzbacher, a brilliant German Jewish chemist who created Doramad, a radioactive toothpaste, in the 1920s.
4 (13:00) **The Dark Confession: Chemical Weapons for the Nazis** - The hosts reveal the story's devastating core: Siegfried escaped the death camps while also producing chemical weapons for the Nazis and developing gas masks that enabled the camps.
5 (19:12) **Siegfried's Decision: 1928 and the Secret Lab** - The episode details how, in 1928, Siegfried accepted a job to head a secret military lab tasked with developing chemical weapons, a direct violation of the post-WWI restrictions on Germany.
6 (23:24) **The Chemical Weapons & The "S-Town"** - Siegfried's lab was in the secret military town of Ranenburg, later known as "S-Town," which also housed a concentration camp and a Nazi nuclear facility.
7 (24:42) **A Jewish Chemist Under Hitler** - Despite being Jewish, Siegfried continued his illegal chemical weapons work for two years after Hitler came to power in 1933, until his family fled to Turkey in 1935.

+ Full timestamped outline available in the app

Show Notes

Wouldn't it be nice if the stories we're told were all true, were all heroic and inspiring? But that's not always the case. Because more often than not, family histories – all our family histories – are messy, complicated, disappointing and sometimes even shameful.

This season on Trapped History, we're looking at some of those stories. And today, we're joined by the writer Joe Dunthorne, whose critically acclaimed book Children of Radium and BBC radio series, Half Life, tell the story of his great-grandfather, Siegfried – and his troubling past which is both visible and hidden at the same time.

It is a must listen.

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