Branches of the Military: The 6 U.S. Armed Forces Explained
The branches of the military explained: the Army, Navy, Marines, Air Force, Space Force and Coast Guard, with founding dates, roles and age limits.
Short answer: There are six branches of the U.S. military: the Army, Marine Corps, Navy, Air Force, Space Force and Coast Guard. The first five sit in the Department of Defense, which now also uses the title Department of War. The Coast Guard sits in the Department of Homeland Security in peacetime and can operate under the Navy in wartime. The National Guard is not a seventh branch. It is the reserve component of the Army and Air Force, with a separate state role.
Last updated: October 28, 2026
Key facts
- Six branches: Army, Marine Corps, Navy, Air Force, Space Force and Coast Guard.
- Oldest: the Army, founded June 14, 1775.
- Newest: the Space Force, founded December 20, 2019.
- The Coast Guard is the only branch outside the Department of Defense in peacetime.
- The National Guard serves both a state governor and the federal government.
The six branches at a glance
The Department of Defense’s Our Forces page lists each service with a one-line description of its role. The founding dates below come from the department’s historic highlights timeline.
| Branch | Founded | Parent department | Main domain | Members are called |
|---|---|---|---|---|
| Army | June 14, 1775 | Defense (Department of the Army) | Land | Soldiers |
| Marine Corps | November 10, 1775 | Defense (Department of the Navy) | Sea-based expeditionary and amphibious | Marines |
| Navy | October 13, 1775 | Defense (Department of the Navy) | Sea | Sailors |
| Air Force | September 18, 1947 | Defense (Department of the Air Force) | Air | Airmen |
| Space Force | December 20, 2019 | Defense (Department of the Air Force) | Space | Guardians |
| Coast Guard | August 4, 1790 (as the Revenue Cutter Service) | Homeland Security | Maritime law enforcement, safety and defense | Coast Guardsmen |
There are only three military departments, not six. The Department of the Navy contains both the Navy and the Marine Corps. The Department of the Air Force contains both the Air Force and the Space Force. Each department has a civilian secretary, while each service has its own four-star chief.
Army
The Army is the oldest and largest branch. It fights on land, from infantry and armor to aviation, air defense and long-range artillery. The Continental Congress created it on June 14, 1775, a year before the Declaration of Independence. Soldiers learn a military occupational specialty after basic training, and the Army’s rank system is covered in our guide to Army ranks in order.
Navy and Marine Corps
The Navy controls the seas. Its carriers, submarines, destroyers and aircraft give the United States a way to move power around the world without needing permission from a host nation. Sailors are trained in a specialty that the Navy calls a rating.
The Marine Corps is a separate service inside the Department of the Navy. It specializes in expeditionary and amphibious operations, which means landing forces from ships and fighting soon after arrival. Marines and sailors often deploy together: Navy ships carry Marine units, and Navy corpsmen serve as medics with Marine infantry.
Air Force and Space Force
The Air Force became independent of the Army on September 18, 1947, under the National Security Act of that year. Its About Us page lists five core functions: air superiority; global strike; rapid global mobility; intelligence, surveillance and reconnaissance; and command and control. It reports a Total Force of more than 689,000 people, counting active duty, Guard, Reserve and civilians.
The Space Force is the newest branch. Its official site says it was established on December 20, 2019, and calls it the first new branch of the armed services since 1947. Its mission is to “secure our nation’s interests in, from, and to space.” It runs satellites for missile warning, navigation and communications, along with the ground stations that track objects in orbit.
Coast Guard
The Coast Guard is both a military service and a law enforcement agency. It traces its origin to the Revenue Cutter Service, which Congress created on August 4, 1790, to enforce customs law at sea. Today it handles search and rescue, drug and migrant interdiction, port security, icebreaking and environmental protection. The Defense Department’s rank insignia page notes that the Coast Guard is part of Homeland Security in peacetime and the Navy in wartime.
Is the National Guard a branch of the military?
No. The National Guard is the Army National Guard plus the Air National Guard, which are reserve components of the Army and the Air Force. What makes the Guard unusual is its dual mission. Guard units usually answer to their state governor for disasters and local emergencies, but the president can federalize them for national missions and overseas deployments.
The other reserve forces work differently. The Army Reserve, Navy Reserve, Marine Corps Reserve, Air Force Reserve and Coast Guard Reserve are purely federal, with no state role.
Who commands the branches?
The service chiefs organize, train and equip their forces. They do not command combat operations. That job belongs to the joint combatant commands, which receive units from every service and answer to the secretary of defense and the president. Our guide to U.S. combatant commands explains how that chain of command works.
How to join a branch
USAGov’s guide to joining the military lists the basic requirements. Applicants must be U.S. citizens or hold a Permanent Resident Card (green card), hold a high school diploma or GED, and take the Armed Services Vocational Aptitude Battery (ASVAB). Age limits differ by branch:
| Branch | Enlistment age range (active duty) |
|---|---|
| Army | 17 to 35 |
| Marine Corps | 17 to 28 |
| Navy | 17 to 41 |
| Air Force | 17 to 42 |
| Space Force | 17 to 42 |
| Coast Guard | 17 to 41 |
Pay is set by grade rather than branch, so a sergeant and a petty officer at the same grade earn the same basic pay. Our military pay chart for 2026 has the figures.
Frequently asked questions
How many branches of the military are there?
Six. They are grouped into three military departments plus Homeland Security, so the count of departments and the count of branches differ.
What is the oldest branch of the U.S. military?
The Army is the oldest. The Continental Congress established it on June 14, 1775. The Navy followed on October 13, 1775, and the Marine Corps on November 10, 1775.
What is the newest branch of the military?
The Space Force is the newest. It was established on December 20, 2019, and sits in the Department of the Air Force.
Is the Coast Guard part of the military?
Yes. It is a full armed service as well as a federal law enforcement agency, which lets its cutters board vessels and make arrests at sea.
Is the National Guard a branch of the military?
No. Guard members wear Army or Air Force uniforms and ranks. A governor can call them up for a hurricane or flood without any federal order.
Which branch is the Marine Corps part of?
The Marine Corps is its own branch, but it belongs to the Department of the Navy, alongside the Navy. It has its own uniformed chief, the commandant of the Marine Corps.
This article was written by Peter with AI assistance and checked against the sources linked. See our AI use disclosure.
Sources
- Department of War: Our Forces
- Department of War: Historic highlights timeline
- U.S. Space Force: About Us
- U.S. Air Force: About Us
- USAGov: Requirements to join the military
