[3] As a young man he joined the German Metal Workers' Association (DMV) and the Social Democratic Party of Germany (SPD).
[4] After the end of his first marriage, from which a daughter emerged, Ziegler married Anna Strauss in 1913, who, like him, embarked on a political career in the SPD.
During the First World War, Ziegler left the SPD in 1916 and joined the Independent Social Democratic Party of Germany (USPD).
In particular, he was accused of showing too cautious a course as a delegate to the trade union conference towards the DMV leadership, which was dominated by the SPD.
In March 1933, one month after the Reichstag fire, Ziegler was arrested and held in a concentration camp for a long time.