In 1914, the Nernsts were entertaining coworkers and students they had brought to their country estate in a private railway car when they learned that war had been declared. Their two older sons entered the army, while father enlisted in the voluntary driver's corps. He supported the German army against their opponent's charges of barbarism by signing the Manifesto of the Ninety-Three, On 21 August 1914, he drove documents from Berlin to the commander of the German right wing in France, advancing with them for two weeks until he could see the glow of the Paris lights at night. The tide turned at the battle of the Marne. When the stalemate in the trenches began, he returned home. He contacted Colonel Max Bauer, the staff officer responsible for munitions, with the idea of driving the defenders out of their trenches with shells releasing tear gas. When his idea was tried one of the observers was Fritz Haber, who argued that too many shells would be needed, it would be better to release a cloud of heavier-than-air poisonous gas; the first chlorine cloud attack on 22 April 1915 was not supported by a strong infantry thrust, so the chance that gas would break the stalemate was irrevocably gone. Nernst was awarded the Iron Cross second class. As a Staff Scientific Advisor in the Imperial German Army, he directed research on explosives, much of which was done in his laboratory where they developed guanidine perchlorate. Then he worked on the development of trench mortars. He was awarded the Iron Cross first class and later the "Pour le Mérite". When the high command was considering unleashing unrestricted submarine warfare, he asked the Kaiser for an opportunity to warn about the enormous potential of the United States as an adversary. They would not listen, Ludendorff shouted him down for "incompetent nonsense." He published his book "The Foundations of the New Heat Theorem".