War Department or Department of War may refer to current and historical ministries of defence, including:

• War Department (United Kingdom), 1747–1857
• War Office, British war department, 1857–1964
• United States Department of War, 1789–1947
• United States Department of Defense, 1949–present (National Military Establishment, 1947–1949); using "Department of War" as a secondary name since 2025

See also

• Ministry of War
• War cabinet

Index of articles associated with the same name

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