Today, the very first airmail service is used to break a siege. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Bismarck's Prussian troops had Paris under siege in September, 1870. They surrounded the city and cut its communication lines. One reason Paris managed to withstand the siege for five months was her airmail service. And since this was 33 years before the Wright Brothers flew, you may well wonder what I'm talking about!

I'm talking about balloons. The first hot air and hydrogen balloons had flown in Paris 86 years before the siege. Balloons had seen their first serious military use ten years before, in the American Civil War. Lincoln set up an air balloon corps in 1861.

For two years the American armies in the East had been pretty static. The Union Army had ten balloons in service most of that time. They rose on tether lines to reconnoiter enemy positions. Some even used telegraphy to communicate with the ground.

Those balloons were useful until the war started moving faster than the few balloons could. The corps disbanded in 1863. But it'd established that you can gather information from the air.

Now, seven years later, Paris had an urgent need to communicate with the outside world. The French were already using tethered balloons to observe the enemy. Now they decided to set up an air mail service. They sent out a call for every existing balloon in Paris and they set up shops for building far more balloons.

In all, 66 balloons left Paris carrying information to France beyond the German lines. Most flights were made at night. In all, the balloons delivered 102 passengers and 11 tons of mail. The mail amounted to 2-1/2 million letters. The balloons also delivered 400 carrier pigeons for return mail. To bring mail back by pigeon, the French outside Paris used early photography to reduce 16 pages of text to a 1¼" by 2" piece of film. But pigeons are unreliable. Only one in eight ever arrived back.

The balloonists had their troubles too -- but less than anyone expected. Two were lost at sea. Six were captured by the Germans when they landed. When others came down behind enemy lines, their pilots managed to deliver the mail anyway. One landed on an island off the coast of Brittany. The most dramatic flight was one that landed in a Norwegian forest after an astonishing 875-mile trip. One flight carried the Minister of the Interior. He landed in an oak tree. But he landed safely nonetheless.

Getting back into Paris was another matter. You can't control where balloons go. So Paris lost an aeronaut on every flight. Several tried to catch favorable winds and fly back in. None succeeded. The very last flight out, made on January 28, 1871, carried news of the Armistice.

So the point had been made. Flight meant communication. This was the harbinger of enormous change. The world had been altered in ways that would reach far beyond one more forgotten war.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

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Mackworth-Praed, B., Aviation: The Pioneer Years. Seacaucus, NJ, Chartwell Books, Inc., 1990, Chapter 2.

For more on balloons in the siege of Paris, see Episode 1492.

An early photo of the first balloon out of Paris during the Siege