As the newly appointed secretary of war, Henry L. Stimson began war mobilization of U.S. industry in 1940. He selected Robert Patterson (1891–1952) as a top assistant. Patterson resigned a federal judge position to become assistant secretary of war. He and Stimson knew each other well. Both were Harvard graduates and Republicans. They also both served in World War I in the same army division in France. During the 1930s they formed an even closer friendship while opposing isolationism in America.

Born in Glens Falls, New York, Patterson followed his father's footsteps into the legal profession by studying law at Harvard. Following graduation, he joined a prestigious law firm headed by Elihu Root (1845–1937), who had been secretary of war and secretary of state between 1897 and 1909. Influenced by Root, Patterson was a strong supporter for national defense. Following World War I, Patterson established a successful New York law firm and did financially well through the economic boom years of the 1920s. In 1930 President Herbert Hoover (1874–1964; served 1929–33) appointed Patterson as a judge to the U.S. District Court of Southern New York. In 1939 President Franklin D. Roosevelt (1882–1945; served 1933–45) appointed Patterson to the U.S. Court of Appeals.

During World War II, Patterson rose to be undersecretary of war. From that position he oversaw the army's multibillion-dollar purchasing program, a highly important position throughout mobilization. Patterson believed military contracts should largely go to major corporations who were already prepared to launch into mass production of war materials. As a result, Patterson forged a strong relationship between the military and big business that persisted into the twenty-first century and greatly influenced American foreign policy. Like Stimson, he staunchly opposed racial segregation in the military services. Following the war, Patterson successfully pushed for all military services to be combined into one department, the newly formed Department of Defense, in 1947. That same year, Patterson resigned from public service and returned to a private law practice. Only five years later, in 1952, he was killed in a commercial airliner crash.