In August 1939 a non-aggression pact between Nazi Germany and the Soviet Union opened the way for a rerun of the Partitions of Poland between the two dictatorships, and this in turn triggered a return to "world war" involving most of Europe which broke out the next month. In 1940 Kretschmann was conscripted for forced labour in Königsberg (Neumarkt) in Brandenburg. He refused to work in a munitions factory and was forced to work on the recently constructed . In 1942 he married Erna Scherff. One source describes this as a "Long-distance wedding" ("Ferntrauung"), but their son was nevertheless born the same year: he died three years later. Between 1941 and 1945 Kurt Kretschmann fought in the German army on the Russian Front. He participated in and survived the Siege of Stalingrad. In the increasingly chaotic closing phase of the war another hearing condemned Kretschmann to death. The sentence was not carried out, possibly because of a Red army attack in which he was wounded. He was then able to return to Germany for home leave, during which time he deserted from the army. Supported by his wife who was able to supply water, vegetables and candles, he hid for 75 winter days in a two-meter wide hole in the ground under a garden summer house, on the site where in 1960 he and his wife would build their home, and which is today designated the "House for the care of Nature" ("Haus der Naturpflege"), at Bad Freienwalde in eastern Brandenburg. He was then captured by the Soviets: between the end of the war in May 1945 and August of that year he was held by the Soviets as a prisoner of war.