Metre Convention
The Great Exhibition in London in 1851 and the Paris International Exhibition in 1867 had shown the need for different nations to use the same units of measurement. In the 1860s there were many discussions by astronomers and surveyors from outside France whether they should use the metre des archives or whether they should use a "new metre" that took account of the 0.03% error. Prussia took the lead in organizing conferences in Berlin to discuss the matter.  France did not take part in the conferences.  Before any actions could be taken the Franco-Prussian War broke out.  Prussia defeated France and the German Empire was formed.