The Franco-Prussian War, 1870-1871, was sparked off by a dispute between France and Prussia over the succession to the throne of Spain. The Prussian army defeated the French at Sedan in September 1870, and captured Emperor Napoleon III. They proceeded to Paris, and secured its capture after a long siege in January 1871. Peace was formalised by the Treaty of Frankfurt in May 1871, which saw France pay indemnity and cede parts of Alsace and Loraine to their conquerors.
From the guide to the Press Telegrams regarding the Franco-Prussian War, 1870-1871, (Cambridge University Library, Department of Manuscripts and University Archives)