The new engines of war brought forth by the recent struggle were peculiarly susceptible to the effects of weather. The larger guns and heavy motor trucks were difficult to move over muddy roads. The aircraft, though they managed to fly in all kinds of weather, suffered innumerable disasters for which atmospheric conditions--chiefly storms and fog--were responsible, and their operations were conspicuously affected by favorable and unfavorable winds. Shells were fired to unprecedented heights, and their trajectories were modified by unknown conditions in the upper air. Last but not least, the use of poisonous gases, especially in the period before gas clouds were largely replaced by gas shells, was dependent upon the occurrence of appropriate winds; and a slight miscalculation in this respect sometimes brought disaster to the troops using the gas. It is not surprising that professional meteorologists played a part in the World War, but it is difficult to understand why meteorological units were not attached to all armies, at least when on active service, several decades before the year 1914. Meteorologists did, indeed, take a hand in one earlier conflict, but not as enrolled soldiers. During the Spanish-American War a special service was organized by the United States Weather Bureau to protect the American fleet in southern waters from unpleasant surprises in the shape of West India hurricanes. In the summer of 1898 a chain of observation stations was established by the Bureau around the Caribbean Sea. The service then inaugurated in consequence of the exigencies of war proved so valuable to shipping in time of peace that it has continued to operate, with some intermissions, down to the present day. When the World War broke out, the only country that immediately put meteorologists, as such, into the field was Germany. The Germans were fortunate in having a far greater number of trained meteorologists at their disposal than had their enemies. There were chairs of meteorology in several German universities and high schools, and the numerous meteorological observatories and institutes of the Empire had provided occupation for a large amount of professional talent in this line. One of the first acts of the army that invaded Belgium was to establish an aerological service in that country.