The Department of Defense was reorganized from which previous department?

The Department of Defense was reorganized from the Department of War, which was the primary military department of the United States government prior to the establishment of the Department of Defense in 1947. The transformation was part of a larger restructuring of the U.S. military and national security apparatus in the wake of World War II, aimed at creating a more unified and coordinated defense strategy. This reorganization included the merging of the departments of the Army, Navy, and the newly created Air Force under the Department of Defense. This move reflected the changing nature of warfare and the need for a comprehensive approach to national security, which was particularly relevant during the onset of the Cold War.