The American Government did not overcome its reluctance to use toxic gases until we had gone forward several months in war preparations, when it was found, just as the English and the French had found, that it would have to be done. It was November, 1917, when ground was broken on a Maryland riverside farm for a huge plant that would produce overwhelming quantities of chlorine, phosgene and mustard gas. When the armistice was signed a year later the three hundred acres were covered with vats and kilns, refrigerators, boilers, steel towers, chimneys, pipe lines, railways, and all the other means for carrying on the most deadly manufacturing processes known to man. For much of the machinery needed there were no existing models and many important parts of the immense plant were designed while it was being built. Experts from the French and British gas factories who came to assist in this development saw it rapidly evolve beyond their own knowledge and stayed to learn rather than to teach. Subsidiary plants were built also, and, altogether, American poison gas factories had a total production, during the last weeks of the war, of an average of two hundred tons per day. The British production, speeded to its highest possible point, was never more than thirty tons per day, the French was much less and the German is supposed to have been between thirty and fifty tons per day. Airplanes had been made and successfully tested for the dropping upon German fortified places, such as Metz and Coblenz, of containers holding a ton each of mustard gas with time fuses fitted for explosion a few hundred feet above the forts. Heavier than air, the gas from each container, settling to earth, would not have left a living thing, human or animal, upon, above or under the ground, within or outside of buildings, on a space the size of a large city block. A new poison gas was developed, far more deadly than any previously in use, and its manufacture carried on with the greatest secrecy. At the end of the war ten tons a day were being produced and it was estimated that a single ton dropped in bombs and containers upon a city of a million inhabitants would have killed them all. Three thousand tons of it were to be ready in the battle zone by March 1, 1919. Knowledge of these preparations and surety of what would, therefore, happen in the early spring of 1919 are believed by military authorities to have been an important factor in the sudden collapse of the German military plans.