After the liberation of South Limburg, two problems arose that needed to be solved urgently. In requisitioned buildings such as schools and castles, large numbers of captured "wrong" Dutchmen such as NSB members and other collaborators were locked up. They had not been convicted and were awaiting punishment by Tribunals and Special Courts. At the same time, there was a severe shortage of miners. Coal was essential to restart the economy. Employment of prisoners was obvious. It came to agreements between mines and Justice. While receiving the same wages as free miners, the prisoners volunteered to work underground, in 1945 in one mine, later in all twelve. Their commitment was accepted by the other miners almost without difficulty. In 1947, National Labor Institutions were established in Eygelshoven, Terwinselen and Treebeek to house the convicts. These institutions led to innovation in the prison system. Prisoners were prepared for return to society. Between 1945 and 1958, more than thirteen thousand political prisoners worked in Limburg mines. In doing so, they made a positive contribution to the reconstruction of the Netherlands.