United States Department of Defense

The United States Department of Defense was established by the National Security Act of 1947 as the institutional center of a unified armed-services structure. Truman had sought such unification since taking office: the law brought the services under a single department and a single Secretary of Defense, while also establishing the Air Force as a separate service, creating the National Security Council, and formally authorizing the Central Intelligence Agency. The change reshaped the organization of power in Washington and gave the presidency a new framework for coordinating national defense.

Creation and Structure

The National Security Act passed on July 25, 1947. Truman had sent the legislation to Congress in February, and its central purpose was to unite the armed services under one department and one cabinet-level secretary. The act did not merely rename an existing office: it reorganized the federal structure for defense and established a common institutional point of leadership for the services.

The same law made two other consequential changes to the national-security framework. It set up the Air Force as a separate military service and created the National Security Council; it also gave formal authorization to the Central Intelligence Agency. These bodies were distinct parts of the new structure, not subdivisions of the department. Their creation alongside the department reflected the breadth of the reorganization: military services, national-security coordination, and intelligence received formal places in the postwar federal system.

Civilian Authority and the War-Effort Debate

The department’s creation followed years in which Truman had treated civilian control of military power as a fundamental principle. While chairing the Truman Committee, he worried that generals and admirals were gaining influence over industry and agriculture as wartime contracts expanded. In a 1942 broadcast, he argued that military leaders should identify what they needed to fight, while decisions about the wider national effort remained in civilian hands. This earlier position was not a description of the later department’s operations, but it illuminates the political concern that accompanied Truman’s pursuit of a unified defense structure: coordination was necessary, yet military expertise did not itself confer authority over national policy.

The 1947 reorganization therefore joined a stronger central structure to the question of who would direct it. A single department and secretary could bring the services under a common administrative leadership, but Truman’s expressed concern about military influence makes clear that unification was not, in his view, a transfer of ultimate political authority from civilian government to the armed forces. His later disputes with military leaders likewise framed civilian command as a constitutional responsibility of the presidency, rather than a matter of organizational convenience alone.

The Department and Defense Readiness

The Korean conflict showed how the department’s responsibilities reached beyond the chain of military command to the industrial base on which military operations depended. During the steel dispute, Secretary of Defense Robert A. Lovett warned Truman that even a short stoppage would increase the risks of the accelerated armament program. He stressed that the combat methods of all three services depended on full use of American industrial facilities, and that troops in Korea were being supported by ammunition rather than exposed to greater danger through shortages.

That advice connected domestic production to defense readiness. Truman regarded the proposed wage increase as a reasonable means of avoiding a strike, while also opposing the steel companies’ demand for a large price increase. He declined to use the Taft-Hartley Act to delay a settlement, believing another eighty days without a change in pay would be unfair to workers who had already remained on the job voluntarily. The episode does not make the department the arbiter of labor policy; instead, it records the defense secretary presenting the military consequences of interrupted production as the administration weighed its response.

Leadership and Institutional Significance

George C. Marshall’s departure marked a notable change in the department’s leadership. Truman announced in September that the Secretary of Defense was leaving office for the final time, and praised his distinguished and patriotic service. The book does not establish how much the attacks by Joseph McCarthy affected Marshall’s decision to retire. It does, however, place his departure amid the loss of other prominent advisers and colleagues, emphasizing how much Truman had relied on Marshall as a steady figure in government.

In retrospect, Truman counted the unified Defense Department among the institutional changes that most altered Washington. He grouped it with the National Security Council and the Central Intelligence Agency as a reorganization of national power that surpassed even the sweeping measures of Franklin D. Roosevelt’s administration. He also distinguished the management of military power from control of nuclear energy: the Atomic Energy Commission, separately, kept nuclear power in civilian hands. Together, these institutional choices show the dual concern running through his defense record—building a more coordinated national-security system while preserving civilian authority over the forces and technologies that system served.