Another fateful spell of weather ushered in the battle of Waterloo. It is described in a well-known passage of “Les Misérables,” which contains enough truth mingled with hyperbole to be worth quoting: “S’il n’avait pas plu dans la nuit du 17 au 18 janvier, 1815, l’avenir de l’Europe était changé. Quelques gouttes de plus ou de moins out fait pencher Napoléon. Pour que Waterloo fût la fin d’Austerlitz, la Providence n’a eu besoin que d’un peu de pluie, et un nuage traversant le ciel à contre-sens de la saison a suffi pour l’écroulement d’un monde.” The rains and floods that led to the annihilation of the Roman legions under Varus in A. D. 9 and the great tempests that helped English seamen defeat the Spanish Armada furnish additional well-known examples of the immense importance of weather as a factor in warfare. We need not, however, look farther back than to the recent world conflict to find similar examples in profusion. Leaving out of consideration the indirect effects of the weather upon the progress of the war as exercised through its control of crops, transportation, and other features in the economic life of the belligerent and neutral nations, we need only examine war-time newspapers to see how the armies themselves were helped or harassed by meteorological conditions at every turn. The war was a great popular teacher of climatography, just as it was of geography. The drenching misery of Flemish winters, as formidable to the soldiers in the trenches as the bullets of the enemy, became as familiar to the present generation of Americans as did somewhat similar conditions in Virginia to Americans of the Civil War period. The British campaigns in Mesopotamia were as much a conflict with climate as with human foes. Marches were made when the temperature stood at 110 degrees Fahrenheit and over. The temperature in the hospital tents is said to have reached 130 degrees. The disaster at Kut-el-Amara was due to the rains and floods that prevented reenforcements from reaching the beleaguered garrison. The failure of the Dardanelles expedition was partly due to the fact that the extreme dryness of the country was not realized--as it would have been if the War Office had called climatologists into council--and totally inadequate provision was made for the water supply.