Simplify the following text for a Grade 4 native English-speaking person.
Original: The Franco-Prussian War or Franco-German War , often referred to in France as the 1870 War ( 19 July 1870 â `` 10 May 1871 ) was a conflict between the Second French Empire and the Kingdom of Prussia .
Simplified: The war started when France declared war on 19 July 1870 . It ended on 10 May 1871 .