The first military use of untethered balloon flight occurring during the French Revolutionary Wars. The French again used observation balloons during the Franco-Prussian War and when Paris was besieged by the Prussians, the balloons became the lifeline for the Parisians.
The first balloon, Neptune, left Paris on the 23 September, 1870 with regular flights beginning 3 days later which were used to carry supplies, passengers and mail.
In order to shoot down these balloons, Alfred Krupp modified a 3.7 cm gun to be mounted on a horse-drawn cart with the breech-loading 37mm canon mounted on a pedestal fixed to the bed of the carriage. The canon had a stock and a folding sight fixed to the receiver. The canon could be rapidly deployed to open fire on the balloons as they crossed Prussian lines.
The Ballonabwehrkanone or balloon defence gun, as the cannon was called, had a modest success- only the balloon Le Daguerre was shot down on 12 November 1870 and the crew taken captive. The balloon had three passengers, Ernest Nobécourt,a pigeon fancier and Louis Pierron, an engineer with his dog. As the balloon overflew the Prussians, it was hit by the gun fire from a Ballonabwehrkanone:
After suffering some Prussian shots, the balloon, whose envelope was pierced in several places is forced to land in disaster. It lands near a farm Ferrières in the vicinity of Lagny in Seine-et-Marne. Nobécourt just has time to throw a mail bag and a cage of pigeons.
In all, five French balloons were captured by the Prussians as they were forced to land, with a further three declared missing.