In 1917, the three companies of Vereinigte Leonische Fabriken Nürnberg-Schweinau, Johann Philipp Stieber based in Roth and Johann Balthasar Stieber & Sohn GmbH based in the Nuremberg district of Mühlhof merged – and established Leonische Werke Roth-Nürnberg AG. The Company went public as early as 1923 to raise more capital. Nearly 80 years later, in 2002, the Company advanced into Deutsche Börse’s M-DAX index.
A change in fashion and the consequences of the First World War led to a dramatic decline in production: there was virtually no demand any longer for such textile products as bourdon stitching, galloon, brocades, tassels and fringes. In the 1920s, Leoni initially refocussed making on electrical wires and strands. Production of enamelled wire and insulated cables then gained significance at the Company’s long-standing facility in Roth. Its customers soon included well-known, major corporations that, alongside civilian products, also made armaments.
The Nazi regime also deployed Leoni for its own purposes during the Second World War. Cables made for telephone communications and motor vehicle manufacture were thus also used in the military sector. Leoni also supplied engine plants and processing industry companies, which were in turn designated as “important to the war effort”.
Plant and machinery was generally well utilised during this time; only the machines for making Lyonese Wares were down because it was illegal to make items of jewellery from copper and silver. Apart from that, the product line-up hardly changed. While much of the male workforce had to serve in the war, it was mainly older and experienced staff who were exempted from military service as “indispensable”.