The United States Assistant Secretary of War was the second–ranking official within the American Department of War from 1861 to 1867, from 1882 to 1883, and from 1890 to 1940. According to the Military Laws of the United States, "The act of August 5, 1882 authorizing the appointment of an Assistant Secretary of War was repealed by the act of July 7, 1884 (23 Stat L., 331) the power conferred by the act of August 5, 1882 never having been exercised," indicating that the post was not filled between 1882 and 1883 (p. 45, footnote 2).
In 1940, the new position of United States Under Secretary of War replaced this position as the number-two office in the department. Assistant Secretary Robert P. Patterson became the first Under Secretary.
The office continued to exercise administrative duties until the department's end in 1947, when the United States Department of Defense was established.
This list only includes those persons who served as the Assistant Secretary, or First Assistant Secretary. At various times, there were also "second" or "third" assistant secretaries, ranking below the Assistant Secretary.
The Air Corps Act of 1926 (44 Stat. 780), passed on July 2 of that year, created a Second Assistant Secretary position in the War Department variously called "Assistant Secretary of War for Aviation," "Assistant Secretary of War for Air," or "Assistant Secretary of War for Aeronautics." Those holding the office, with an eigh-–year vacancy between 1933 and 1941, were F. Trubee Davison (1926–1933), Robert A. Lovett (1941–1945), and Stuart Symington (1946–1947).
William Moulton Ingraham, Assistant Secretary of War under President Wilson and a former Mayor of this city, died today at his home after a brief illness. He was 80 years old. ...
William Reid Williams, Assistant Secretary of War under President Woodrow Wilson and prominently identified with the business and social life of Richmond, died tonight. He was 65 years old
Frederick Huff Payne, Assistant Secretary of War under former President Herbert Hoover, died today at the home of his son, Groverman. He was 83 years old.