The United States Military: An Overview of the Army, Navy, Air Force and Marines

MilitaryOn occasion, private investigators may land cases that involve brushing up against one or more of the branches of the United States Military. For example, a private investigator might be hired to investigate the background of someone in the armed forces and lookup military records. In another situation, a private eye may be asked to track someone who is currently serving (see How to Find Someone Who is Serving in the Military). Whatever the reason, it is helpful to have a basic understanding of the branches.

This article provides a brief overview of each branch of the military and suggests some additional resources if you’d like to get more information.

The Army

The United States Army is the branch of the United States Military responsible for land-based military operations.  The U.S. Army is the largest and oldest established branch of the U.S. military and is one of seven uniformed services. The modern Army has its roots in the Continental Army which was formed on 14 June 1775, before the establishment of the United States, to meet the demands of the American Revolutionary War. Congress created the United States Army on June 14, 1784 after the end of the war to replace the disbanded Continental Army. The United States Army considers itself to be descended from the Continental Army and thus dates its inception from the origins of that force.

The primary mission of the Army is to “provide necessary forces and capabilities in support of the National Security and Defense Strategies.” Control and operation of the U.S. Army is administered by the Department of the Army, one of the three military departments of the Department of Defense.

The civilian head of the US Army is the Secretary of the Army.  The highest ranking military officer in the department is the Chief of Staff, unless the Chairman of the Joint Chiefs of Staff or Vice Chairman of the Joint Chiefs of Staff are Army officers. Following are a few key stats:

  • In 2008, the Army had 539,675 soldiers
  • The Army National Guard (ARNG) reported 360,351 soldiers
  • The United States Army Reserve (USAR) reported 197,024 soldiers
  • The combined component total is approximately 1,097,050 soldiers

For more up-to-date statistics, please visit one of the official Army websites listed below.

Army-related Websites

The most useful website is the United States Army Website. It provides information and resources about the US Army, News, information on life in the military.  The site also provides interesting information on Army aircraft, weapons and vehicles. Other helpful website include the U.S. Army Reserve Recruiting, which provides information on Army Reserve service options, careers, training, and employment opportunities. Another good site is the Association of The United States Army, which serves as an educational organization that supports America’s Army – Active, National Guard, Reserve, Civilians, Retirees and family members

  • Army Gift Program – This Web site provides the American public with information on methods by which citizens, organizations, and corporations can contribute cash or goods and services to benefit Soldiers and their Families.
  • Army Outreach – Provides a user-friendly way for the public to find Army events, access resources and request support for events.
  • Army Publications – The Army Publishing Directorate is the Army’s leader in publishing and distributing information products, employing advanced technologies to ensure responsive support worldwide. Their primary mission is supplying official authenticated information to enhance the readiness of the total force.
  • Army Recruiting Command – Responsible for manning both the Active Army and the U.S. Army Reserve, ensuring security and readiness for our Nation. Recruiting operations are conducted throughout the United States, Puerto Rico, the Virgin Islands, Guam, American Samoa, and at U.S. facilities in Germany and Asia.
  • Army War College – Prepares selected military, civilian, and international leaders for the responsibilities of strategic leadership in a joint, interagency, intergovernmental and multinational environment.  The U.S. Army War College – the college and its associated institutes – operate as a synergistic team in support of Army War College students and alumni: all those serving as strategic leaders for our Soldiers, Sailors, Airmen and Marines.
  • US Army Center of Military History – Provides information on the History of the U.S. Army.
  • U.S. Military Academy (West Point) – Renowned as the world’s premier leader development institution, West Point accomplishes its mission by developing cadets intellectually, physically, militarily, ethically, spiritually, and socially. The student body, or Corps of Cadets, numbers 4,400 and each year approximately 1000 cadets join the Long Gray Line as they graduate and are commissioned as a second lieutenant in the U.S. Army.

United States Marine Core (USMC)

The United States Marine Corps (USMC) is a branch of the United States armed forces responsible for providing force projection from the sea. This branch of the military uses the mobility of the United States Navy to rapidly deliver combined arms task forces to combat zones around the world. The branch is one of seven uniformed military services of the United States.

The Marine Corps is a component of the Department of the Navy, and often works closely with U.S. naval forces for training, transportation and logistic purposes; however, in the military leadership structure the Marine Corps is a separate branch.

Marine Core Websites

If you’re looking for more information, following is a list of some of the most popular websites and resources. The best place to start is the Marine Corps Website, which is the official website of the United States Marines. Here, you’ll find information on all aspects of this branch of the military. You’ll find information on the history, the organization structure and the responsibilities of the corp. Of course, you can also find details on starting a career in the corp. If that is what you’re searching for, you may actually want to begin your search at, which is the official recruiting site. If you expect to enter the military at an officer level, check out Other helpful resources include:

  • Corps Reserve – This is the official website of the reserve. The mission of Marine Forces Reserve (MARFORRES) is to augment and reinforce active forces in time of war, national emergency or contingency operations, provide personnel and operational tempo relief for the active forces in peacetime, and provide service to the community.
  • Marine Corps Association – For all who have earned and worn the eagle, globe, and anchor, the Marine Corps Association is the professional organization for all Marines—active duty, Reserve, retired, and veterans. The MCA understands and identifies with the sacrifices made and the services rendered to this great country.
  • Marine Corps JR ROTC – The Junior Reserve Officers’ Training Corps (JROTC), like its senior counterpart ROTC came into being with the signing of the National Defense Act. The act authorized high schools the loan of federal military equipment and the assignment of active or retired military personnel as instructors on the condition that they followed a prescribed course of training. At its inception, the JROTC course consisted of a minimum of three hours of military training per week for a period of three years. Any JROTC graduate who completed this course of military instruction was authorized a certificate of eligibility for a reserve Commission to be honored at age 21.
  • Corps Band – Founded in 1798 by an Act of the United States Congress, “The President’s Own” United States Band is America’s oldest professional musical organization. Today, “The President’s Own” is celebrated for its role at the White House and its dynamic public performances. “The President’s Own” encompasses the United States Band, Chamber Orchestra, and Chamber Ensembles, and performs regularly at the White House and for more than 500 public performances across the nation each year.

The Navy

The United States Navy is a branch of the United States armed forces military that is responsible for conducting naval operations. The mission of the United States Navy is “to maintain, train and equip combat-ready Naval forces that are capable of winning wars, deterring aggression and maintaining freedom of the seas.” As of this writing, the U.S. Navy has nearly 500,000 personnel on active duty or in the Navy Reserve and operates 278 ships in active service and more than 4,000 aircraft.

The United States Constitution provided the legal basis for a seaborne military force by giving Congress the power “to provide and maintain a navy.”  In 1974, Congress passed the Naval Act of 179 which order the construction and manning of six frigate ships.

The U.S. Navy came into international prominence in the 20th century, especially during the second World War. Operating in both the European and Pacific waters, this branch of the military was a part of the conflict from the onset of American military involvement from the attack on Pearl Harbor to Japan’s official surrender aboard the USS Missouri.

The Navy played a key role in the Cold War, where it evolved into a nuclear deterrent and crisis response force while preparing for a possible global war with the Soviet Union.

The Navy maintains a sizeable and consistent presence in the world, deploying ships to such areas as East Asia, Southern Europe, and the Middle East.  The Navy’s ability to project a show of force to the regions of the world, engage in forward areas during peacetime, and rapidly respond to regional crises makes it an active player in American foreign and defense policy.

The Department of the Navy has three principal components:

  • The Navy Department, which consists of executive offices, located primarily in Washington, D.C.
  • The operating forces, including the Marine Corps, the reserve components
  • In times of war, the U.S. Coast Guard (in peace, a component of the Department of Homeland Security) and the shore establishment

Naval Websites

  • Official Website of the U.S. Navy – The official website provides information on the history, contact information, how to enlist, and much more.
  • – Provides information about this important branch of the military, how to find jobs, start careers and how to pursue other opportunities.
  • The Naval Historical Center – The Naval History & Heritage Command is the official history program of the Department of the Navy. Its lineage dates back to 1800 with the founding of the Navy Department Library by President John Adams. The Command now includes a museum, art gallery, research library, archives, underwater archaeology and curator as well as research and writing programs.

The Air Force

The United States Air Force (USAF) is the aerial warfare, space warfare, and cyber warfare branch of the United States armed forces and is one of the American uniformed military services. Initially part of the United States Army, the United States Air Force was formed as a separate branch of the military under the National Security Act of 1947. The U.S. Air Force is the most recent branch of the U.S. military to be formed.

The U.S. Air Force provides Global Vigilance, Global Reach, and Global Power, with manned aircraft, unmanned combat air vehicles, air-launched cruise missiles, and intercontinental ballistic missiles. The United States Air Force has personnel on active duty, in the Selected and Individual Ready Reserves, and in the Air National Guard. In addition, the USAF employs civilian personnel, and has auxiliary members in the Civil Air Patrol.

The Department of the Air Force is headed by the civilian Secretary of the Air Force who oversees all administrative and policy affairs. The Department of the Air Force is a division of the Department of Defense, which is headed by the Secretary of Defense. The highest ranking military officer in the Department of the Air Force is the Chief of Staff of the Air Force.

Following are websites that provide more information about the USAF:

  • The Official Website of the U.S. Air Force – The official website provides a wealth of information on the aviation branch of the military. Learn about how to start a career, how to find someone in the service and access plenty of resources for those who are interested in joining.
  • United States Air Force – Learn about the history of the Air Force, explore opportunities to join, get information on the latest news and events.
  • USAF Honor Guard – Since its earliest years the USAF Honor Guard has led the way as the representatives of all Airmen in ceremonies and events. These men and women of The USAF Honor Guard “…represent every member, past and present of the United States Air Force…” Now, in our 60th Anniversary year and still serving as one of the Air Force’s oldest organizations, the Honor Guard continues to serve the Chief of Staff.
  • Airmen from every enlisted rank and both company & field grade officers volunteer and are competitively selected from their peers in over 45 different career fields to make the Honor Guard the standard of discipline and military professionalism.

Other Key Departments and Operations