 Giertz supported the military campaign, sending money and materials and, after the Moscow Peace Treaty had ceded one-eleventh of Finland's territory to the Soviet Union, receiving Finnish refugees.During the latter part of Nazi Germany's occupation of Denmark his own home also became a safe house for members of the Danish resistance movement who were being hunted by the Nazis and had fled their country.Giertz's brother was architect Lars Magnus Giertz (1908-2008).