The **United States Department of War** was a historic Cabinet department responsible for managing the U.S. Army and, initially, naval affairs before the creation of separate departments for the Navy and Air Force. Established on August 7, 1789, it served as the primary federal institution overseeing military operations for 158 years until it was reorganized under the National Security Act of 1947, which split it into the Department of the Army and the newly formed Department of the Air Force[1][3]. Originally called the War Department and sometimes the War Office, it managed the Army's operation and maintenance, as well as naval affairs from 1794 until the Navy Department's establishment in 1798. It also oversaw most non-naval air forces until the Air Force became its own department in 1947[1]. The department was headed by the Secretary of War, a civilian official responsible for military finance, procurement, and limited military direction. Key historical milestones linked to the department include its role during foundational conflicts like the Revolutionary War, the Korean War, and the Vietnam War, where it coordinated U.S. military efforts. Following World War II and the National Security Act, the War Department’s functions were consolidated into the Department of Defense in 1949, which unified the Army, Navy, and Air Force under a single Secretary of Defense[3]. In modern context, there has been a recent executive order in 2025 aimed at restoring the Department of War name to replace the Department of Defense, emphasizing a stance of deterrence through strength and signaling a shift in military policy and branding[4]. This initiative includes restructuring commands and submitting legislative proposals to effect the change. Today, the Department of War (or its contemporary equivalent) remains America’s largest government agency, coordinating all military branches including the Army, Marine Corps, Navy, Air Force, Space Force, and National Guard to ensure national security and military readiness[5]. It continues to emphasize technological innovation, acquisition, and operational