U.S. President Donald Trump announced on Monday his administration’s intention to rename the Department of Defense (the Pentagon) to the “War Department” within approximately a week. Trump and Defense Secretary Pete Hegseth have expressed regret over the name change that occurred after World War II, aiming to restore the “warrior spirit” within the department. Historically, the War Department existed from 1789 until 1947, when President Harry Truman split it into the Army and Air Force and merged it with the previously independent Navy to form the Department of Defense. Truman’s renaming aimed to centralize authority over the separate military branches, especially the Navy. The article also outlines key historical milestones including the establishment of the Continental Army in 1775, the Navy, and the Marine Corps, the adoption of the Declaration of Independence in 1776, the Treaty of Paris in 1783, and the construction and opening of the Pentagon building in 1943.

The National Security Act of 1947 and its 1949 amendment formally created the Department of Defense and expanded the powers of the Secretary of Defense.