Dated 1861, it appears King William I of Prussia had these made in that year to be awarded from then onwards to Prussians and selected foreign individuals for their contribution to military alliances, joint operations or civil achievements such as international engineering projects. The 1st Class Cross was awarded a total of 20 times between 1867 and 1871 with 19 going to non-Prussians. Although the reason for honouring Justus with this medal is not known for certain, the French Engineer Ferdinand de Lesseps also received one for being the principe builder of the Suez Canel, so it is likely that Justus was awarded the medal for his work on the same project.