3.2 Military Departments (AFH-1 Section 5B)

Military Departments (AFH-1 Section 5B)

Quick Answer: There are three military departments—Army, Navy, and Air Force—not six. The Department of the Navy includes the Marine Corps and, in wartime, the Coast Guard. The Department of the Air Force includes the Space Force. The six U.S. Armed Forces are the services those departments organize, train, and equip.

AFH-1 Figure 5.1 is the department picture; paragraph 5.4 is the caption. E5 and E6 testing is ADTC level B.

Defending the nation

Since the nation's birth, the military has had the constitutional duty to ensure national survival, defend lives and property, and promote vital interests at home and abroad. Jointly, senior military leaders underwrite the strategy of defending the homeland and assuring allies, while dissuading, deterring, and defeating enemies.

The military departments consist of the Army, the Navy (including the Marine Corps and, in wartime, the Coast Guard), and the USAF (including the Space Force). That is three civilian-led departments, not one department per uniform.

Services versus departments versus combatant commands

Keep this comparison in working memory. Section 5C fills the combatant-command column; 5B is where people lose the department count.

The Coast Guard is a military service and a branch of the U.S. Armed Forces at all times. In peacetime it is in the Department of Homeland Security. It operates as part of the Navy on declaration of war or when the President directs. Do not park the Coast Guard in the Department of the Navy on a peacetime stem.

Key West Agreement — three general functions

The Secretary of Defense and the Joint Chiefs of Staff established general and specific functions (roles and missions) of each branch in the Key West Agreement of 1948. The latest revision, 1958, states three general functions of the U.S. Armed Forces: (1) support and defend the U.S. Constitution against all enemies, foreign and domestic; (2) ensure, by timely and effective military action, the security of the United States, its possessions, and areas vital to its interests; and (3) uphold and advance the national policies and interests of the United States.

Each service shall observe those principles, fulfill its specific functions, and use the other services' personnel, equipment, and facilities where economy and effectiveness will be increased.

Specific functions you must not swap

Army. Land-based branch. Mission: "To fight and win our nation's wars by providing prompt, sustained land dominance across the full range of military operations and the spectrum of conflict in support of combatant commanders." It prepares land forces for war, expands peacetime components, and develops Army weapons, tactics, technique, organization, and equipment while coordinating with the Navy and USAF on amphibious and airborne concerns. Organize, train, and equip land forces for (1) operations on land, including joint operations; (2) seizure or defense of land areas, including airborne and joint amphibious operations; and (3) occupation of land areas.

Navy. Mission: maintain, train, and equip combat-ready naval forces capable of winning wars, deterring aggression, and maintaining freedom of the seas. It includes naval combat and service forces, naval aviation, and the Marine Corps, and is organized primarily for prompt and sustained combat at sea. AFH-1 calls it the largest, most capable navy in the world, with the highest combined battle fleet tonnage and the world's largest aircraft carrier fleet. Organize, train, and equip naval forces for: (1) operations at sea, including joint operations; (2) control of vital sea areas, protection of vital sea lanes, and suppression of enemy sea commerce; (3) support of occupation forces as required; (4) seizure of minor enemy shore positions reducible by landing forces within the fleet organization; (5) naval reconnaissance, antisubmarine warfare, and protection of shipping.

Marine Corps. Functions: (1) Marine forces with supporting components for seizure or defense of advanced naval bases and limited land operations in connection therewith; (2) with the Army and USAF, develop amphibious landing-force tactics, technique, and equipment; (3) detachments on armed Navy vessels; (4) security detachments for naval property at naval stations and bases; (5) as directed, missions and detachments in foreign countries to support national policies and interests. The Marine Corps also assists the Army and the USAF in accomplishing their missions.

Air Force. The USAF and Space Force are the nation's principal air and space forces. The Department of the Air Force organizes, trains, equips, and provides air, space, and cyberspace forces for prompt and sustained combat operations, military engagement, and security cooperation, and to support the other Military Services and joint forces. Together they provide global vigilance, global reach, and global power. Organize, train, and equip air forces for: (1) air operations including joint operations; (2) gaining and maintaining general air supremacy; (3) establishing local air superiority where and as required; (4) the strategic force of the United States and strategic air reconnaissance; (5) airlift and support for airborne operations; (6) air support to land and naval forces, including occupation forces; (7) air transport for the U.S. Armed Forces, except as provided by the Navy; (8) developing weapons, tactics, technique, organization, and equipment of USAF combat and service elements, coordinating with the Army and Navy on amphibious and airborne operations.

Space Force. Within the Department of the Air Force, the Space Force shall develop concepts, doctrine, tactics, techniques, and procedures and organize, train, equip, and provide forces to: (1) provide freedom of operation for the United States in, from, and to space; (2) provide prompt and sustained space operations; (3) protect the interests of the United States in space; (4) deter aggression in, from, and to space; and (5) conduct space operations.

Coast Guard. Major functions: (1) enforce or assist in enforcing applicable federal laws on, under, and over the high seas and waters subject to U.S. jurisdiction; (2) maritime air surveillance or interdiction to enforce U.S. laws; (3) administer laws and enforce regulations for safety of life and property on and under those waters for matters not specifically delegated to another department; (4) develop, establish, maintain, and operate, with due regard to national defense, aids to maritime navigation, icebreaking facilities, and rescue facilities; (5) pursuant to international agreements, icebreaking facilities on waters other than the high seas and U.S.-jurisdiction waters; (6) oceanographic research of the high seas and waters subject to U.S. jurisdiction; and (7) maintain a state of readiness to function as a specialized service in the Navy in time of war, including Maritime Defense Zone command responsibilities.

Lock the department count first, then which service sits in which department. Do not give the Army occupation function to the Marine Corps or the Space Force space-functions list to the Air Force.