During World War II, the Allied military forces faced severe problems integrating equipment, tactics, and logistics into successful combat operations. To help confront these problems, scientists and engineers developed new means of studying which equipment designs would best meet the military's requirements and how the military could best use the equipment it had on hand. By 1941 they had also begun to gather and analyze data from combat operations to improve military leaders' ordinary planning activities. In 'Rational Action', William Thomas details these developments, and how they gave rise during the 1950s to a constellation of influential new fields, which he terms the 'sciences of policy', that included operations research, management science, systems analysis, and decision theory.