Siege of Paris balloon factory. 19th-century illustration of balloons being manufactured in the Gare d'Orleans (now the Gare d'Austerlitz) train station, Paris, France. These balloons are for use in the Siege of Paris during the Franco-Prussian War (July 1870-May 1871). Balloons were used to send mail. During the siege, 168 people, 3 million letters, 363 pigeons, and 5 dogs, left Paris on 66 balloons. The factory at the Gare d'Orleans was supervised by French balloonist Eugene Pierre Godard.