With the commencement of the Second World War, the mobilization and organization of industrial labour forces was the greatest challenge confronted by all participating nations. This was an economic, social, and above all political challenge. This chapter outlines the changes made to the labour systems in the six nations, namely, the USA, Great Britain, the Soviet Union, Germany, Italy and Japan. In all six nations, workers' associations confronted fundamental changes in the industrial workforce's infrastructure. Rearmament and the commencement of hostilities eliminated any residual unemployment caused by the Great Depression. Since changes in the three Axis powers were the most pronounced, the chapter pays particular attention to Germany, Italy and Japan. The chapter explains the mobilization of previously untapped labour sources, addressing how it changed the industrial workforce's composition and daily life in the workplace. It highlights the mobilization of female workers and foreign labourers in Germany and Japan.