The son of a carpenter who died when he was 8, Grünewald apprenticed as a baker but found work difficult to come by when the First World War ended and the demobilised soldiers entered the labour market.[1] Attracted to the nationalist propaganda prevalent at the time Grünewald joined the Freikorps before signing on with the army for a 12-year stint.[1] Leaving the army as a staff sergeant in April 1931 Grünewald again struggled to find employment and so joined the Sturmabteilung.