https://crsreports.congress.gov
Updated February 8, 2022
Defense Primer: The Military Departments
Military Departments
The three military departments within the Department of
Defense (DOD), created by the National Security Act of
1947, are the Department of the Army, the Department of
the Navy, and the Department of the Air Force (P.L. 80-
253). A military department prepares and provides
strategic, conventional, and special operations forces for
military operations conducted by DOD. Each department
has an executive headquarters for administering its
activities, personnel, and organizations. The type and
number of personnel permitted to work in an executive
headquarters are limited by law and differ among the three
departments (Table 1).
Table 1. Executive Headquarters Personnel Limits
Department of the Air Force
Source: 10 U.S.C. §§7014, 8014, 9014.
Note: Personnel limits do not apply in time of war and they may be
increased by 15% of such limits in time of national emergency.
Secretary of the Military Department
The military departments are led by a civilian secretary
whom the President of the United States appoints with the
advice and consent of the Senate. The authority of a
secretary runs from the President through the Secretary of
Defense. The secretaries of the military departments are
responsible for training, equipping, and organizing their
departments’ armed services. A secretary may present
departmental recommendations to Congress after notifying
the Secretary of Defense. Principal officials of the
department reporting to a secretary include the under
secretary, assistant secretaries, and general counsel. These
officials typically are appointed by the President with the
advice and consent of the Senate. Specific areas of
responsibility for the assistant secretaries include logistics,
manpower, acquisition, and financial management.
Department of the Army
The Office of the Secretary of the Army administers the
Department of the Army; secretarial authorities are set forth
in 10 U.S.C. §7013 (see below). The department’s armed
service is the Army, which is the principal land force in
DOD. The Army is composed of the Regular Army, Army
Reserve, and Army National Guard of the United States.
The Department of the Army’s FY2022 budget request is
$173 billion. The total numbers of actual or estimated
personnel in the Department of the Army for FY2020,
FY2021, and FY2022 are in Table 2.
Office of the Secretary of the Army
Service Chief and Service Staff
Source: CRS analysis of military department statutory authorities.
Table 2. Department of the Army Personnel
Source: DOD, Defense Manpower Profile Report – Fiscal Year 2022,
July 2021, pp. 2-3 (FY2020 Reserve and National Guard data rounded
by source).
Department of the Navy
The Office of the Secretary of the Navy administers the
Department of the Navy; secretarial authorities are set forth
in 10 U.S.C. §8013 (see below). The department’s armed
services are the Navy and the Marine Corps, which are the
principal maritime forces in DOD. The Navy is composed
of the Regular Navy, Fleet Reserve, and Navy Reserve. The
Marine Corps is composed of the Regular Marine Corps,
Fleet Marine Corps Reserve, and Marine Corps Reserve.
The Department of the Navy’s FY2022 budget request is
$211.7 billion. The total numbers of actual or estimated
personnel in the department for FY2020, FY2021, and
FY2022 are in Table 3.
United States Coast Guard
The Coast Guard is an armed service normally operating in the
Department of Homeland Security (DHS). It has contingent
roles in DOD as a principal maritime force. During wartime, or
if directed by the President, the Coast Guard would transfer
from DHS to the Department of the Navy (14 U.S.C. §103).
