In 1870, Paris was surrounded by the Prussian army and no communication with the provinces was possible. The government had taken refuge in Tours and carrier pigeons were not enough to get news from the capital. A service of balloon-posts which transported several tens of kg of mail beyond the Prussian lines was then set up. The mail bags were hung on the outside of the wicker basket with the ballast bags. During the siege of the city, 64 mail balloons left Paris from the four improvised “ports” at the Gare de l’Est, Gare d’Orléans, Gare du Nord and Place Saint-Pierre in Montmartre.