World War I marked the first large-scale mobilization of science for military purposes. Prior to the war, the American military ran a few small laboratories as well as the Bureau of Standards, but independent inventors and industrial firms predominated. Similarly in Europe, military-directed scientific research and development was minimal. The powerful new technologies that led to trench warfare, however, reversed the traditional advantage of fast-moving offensive tactics; fortified positions supported by machine guns and artillery resulted in high attrition but strategic stalemate. Militaries turned to scientists and engineers for even newer technologies, but the introduction of tanks and aircraft had only a marginal impact; the use of poison gas made a tremendous psychological impact, but decisively favored neither side. The war ultimately turned on maintaining adequate supplies of materials, a problem also addressed by military-funded science—and, through the international chemical industry, closely related to the advent of chemical warfare.