Ernst Jakob Homberger, a director of the Schaffhausen engineering firm Georg Fischer, married Bertha Marguerite Rauschenbach and, after the death of his father-in-law Johannes Rauschenbach-Schenk in 1905, became the only authorised signatory of the watch factory held by the Rauschenbach heirs, among them Carl Gustav Jung. He guided IWC through the First World War and the Depression and, shortly before the 1929 crash, became sole proprietor, renaming the firm Uhrenfabrik von Ernst Homberger-Rauschenbach. He founded housing and welfare funds for staff, the J. Rauschenbach Foundation (1929) and the Watch Company Welfare Foundation (1949). Under him IWC made the Special Pilot's Watch (1936), the Portugieser (1939), the Big Pilot's Watch (1940) and the Mark 11 (1948). He received an honorary doctorate from the University of St. Gallen in 1952 and died in 1955, aged 85.