The Franco-Prussian War saw the Germans completely surround Paris for more than four months in 1870. Balloon mail was the only way communications from Paris could reach the rest of France, with dozens of flights made, mostly at night, and hundreds of thousands of letters delivered.

One of them has been discovered by the National Archives, penned in French on December 6, 1870 by a man named Charles Mesnier (or Mesmier) to his mother, care of Monsieur Grussin (or Grossin) at 8 Place de la Ville, Pont-Audemer, in Normandy.

"It's a intriguing human element to an important piece of history," National Archives assistant director-general Louise Doyle told media.

The letter was transferred to the archive's Brisbane office from the former Queensland Post and Telegraph Museum in 2001, but there is no information about its origin.

It came to light recently as part of a joint project between the National Archives of Australia and the Archives Nationales in France. In the letter, which is full of fervour, the man assures his mother he is in good health.

Latest News from World News Desk