It is usually accepted that warfare is a direct stimulus to scientific advancement. Arms races and conflicts act as a spur for scientific exploration, and many inventions that seem essential today - canned food, microwave ovens and digital photography among them - were born out of military necessity.
During the Franco-Prussian War, the French population had unwavering faith in the ability of their greatest minds to deal with the Prussian threat. Their world-leading scientists would find new ways to feed them, arm them and destroy the Prussian invaders.
However, the French scientific community failed to deliver, especially during the siege of Paris. Partly this was due to the speed with which events spiralled out of control. There was no time for a leisurely consideration of ideas and lengthy trials of the more promising ones - matters had reached a critical point almost before anyone knew what was happening.