[2] Poelchau attended the Ritterakademie Gymnasium in Liegnitz, where he participated in Bible classes and became involved in the German Youth Movement (Jugendbewegung), which influenced him to turn away from a rural conservative piety.

[3] The couple married on 12 April 1928, lived in Berlin and cultivated a large group of friends and acquaintances, that proved highly valuable after the handover of power to the Nazis.

[2] In 1931, he passed his second state exam in Berlin and wrote his doctoral thesis under Tillich titled: Die sozialphilosophischen Anschauungen der deutschen Wohlfahrtsgesetzgebung (The Social Philosophical Views of German Welfare Legislation).

[2] The paper was published in 1932 as a book titled Das Menschenbild des Fürsorgerechtes: Eine ethisch-soziologische Untersuchung (The Image of Man in the Law of Welfare: An Ethical-Sociological Investigation).

These included Gertie Siemsen, a long-time friend from his student days, Willi Kranz, canteen manager in the Tegel and Plötzensee prisons and his partner Auguste Leißner, Hermann Sietmann and Otto Horstmeier, two former political prisoners, the couple Hildegard and Hans Reinhold Schneider who worked in social welfare and taught school (they were the parents of [Gesine Schwan] who later became a political scientist).

[11] In 1942, the Soviet led Red Orchestra espionage network was uncovered by the Abwehr in Germany, France and the Low Countries[12] and many of its members were imprisoned and executed.

Poelchau provided support for Arvid and his American wife Mildred Harnack, John Rittmeister, Harro and Libertas Schulze-Boysen, Kurt and Elisabeth Schumacher, Walter Husemann, Adam Kuckhoff, and many others.

One Jewish family, Manfred and Margarete Latte with their son Konrad, fled from Breslau after they learned they were to be deported, to Berlin where they went into hiding.

[13] As Konrad Latte was of a typical age to be conscripted[13] Poelchau filled in a registration card for the Volkssturm, a national militia that was independent of the German army, to provide a cover ID.

[13] Konrad Latte, established contact between Poelchau and Ruth Andreas-Friedrich,[13] the co-founder of the resistance group Onkel Emil [de], along with the conductor Leo Borchard.

The siblings managed to escape the Große Hamburger Straße deportation collection camp and make their way back to Poelchau's door.

In 1945, he co-founded the Aid Organisation of the Protestant Churches [de] (Hilfswerk der Evangelischen Kirchen) in Stuttgart, together with the theologian and resistance fighter Eugen Gerstenmaier[26] and became its General Secretary.

The Aid Organisation took care of the problems of refugees, the construction of apartments (settlement work) and homes for the aged and apprentices, and emergency churches.

After returning to Berlin in 1946, Poelchau became involved in reforming the prison system in the Soviet occupation zone as councillor of the Central Administration of Justice.