The Franco-Prussian War was a war between France and Prussia. Some German allies of Prussia also joined. This war was provoked by Otto Von Bismarck, the Prussian Chancellor. He wanted to unite Germans by making them fight together against a common enemy. Bismarck did this by irritating the Emperor of France, Louis-Napoléon Bonaparte (Napoleon III). The war started when France declared war on 19 July 1870. It ended on 10 May 1871. Prussia won.