After marrying Arvid Harnack , she moved to Germany in , where she began her career as an academic. Mildred Harnack spent a year at the University of Jena and the University of Giessen working on her doctoral thesis. At Giessen, she witnessed the beginnings of Nazism. Mildred Harnack became an assistant lecturer in English and American literature at the University of Berlin in In , Mildred and her husband Arvid began to resist Nazism.
Mildred nicknamed the underground resistance group they established "the Circle. Between and , the couple's group intersected with three other anti-fascist resistance groups. The most important of these was run by Luftwaffe lieutenant Harro Schulze-Boysen. Like numerous groups in other parts of the world, the undercover political factions led by Harnack and Schulze-Boysen later developed into an espionage network that collaborated with Soviet intelligence to defeat Hitler.
The couple were arrested in September and executed shortly after. Mildred Elizabeth Fish was born and raised on the west side of Milwaukee, Wisconsin. Mildred had three siblings, Harriette the eldest , and twins Marbeau aka "Bob" and Marion. After the death of her father, Mildred and her mother moved to Chevy Chase, Maryland where Mildred's eldest sister lived.
There she attended Western High School her senior year. She played on the basketball and baseball teams, served as editor for The Trailblazer , and played the role of Princess Angelica in William Makepeace Thackeray 's The Rose and the Ring , the senior class play. During her first year, she worked for the Wisconsin State Journal as a film and drama critic to support herself. She stayed at a rooming house popular with journalists and writers, but left after facing some mild prejudice, which caused her to change her major from journalism to humanities, then later to English literature.
In , she became a staff writer for the Wisconsin Literary Magazine. On June 22, , she was awarded a Bachelor of Arts in Humanities. While Mildred was a graduate student at the University of Wisconsin, she met Arvid Harnack , a graduate student from Germany who was studying under a Rockefeller Fellowship. He subjected Fish-Harnack to a grueling scrutiny that shaped her intellectual outlook.
