Theodor Strünck studied legal science, graduating at the University of Rostock in 1924, and became a lawyer (later a director) at an insurance company. Initially sympathising with National Socialism, he then turned to opposing the regime on their seizure of power and the subsequent decline in the rule of law. In 1937 he became a Hauptmann in Germany's reserve forces, working in the Wehrmacht section of the Amt Ausland/Abwehr under Hans Oster. He came into contact with Carl Goerdeler and organised meetings of German Resistance members in his own home.
