U.S. Military 101

Updated: March 8, 2021
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    Just prior to the American Revolution of 1776, the Continental Congress passed laws creating a Continental Army, Navy, and Marine Corps, with General George Washington as the Commander-in-Chief.

    U.S. Military 101 The earliest days of the U.S. military were a bit like today–there wasn’t a coalition, per se, but U.S. troops were supported by French soldiers during the war. It would be a sign of things to come with multinational support during both World Wars and beyond.

    But 1776 is a long way from today’s American military. What started out as little more than state militias evolved into a sophisticated global power responsible (in partnership with other nations) for national security but also a wider umbrella of protection, peacekeeping, and counterterror efforts with the U.N. and partner nations.

    The U.S. Military In The 21st Century

    Today’s military is a bit of a complicated beast. The Department of Defense (DoD) is the federal agency responsible for the Army, Navy, Air Force, Space Force, and Marine Corps. The United States Coast Guard is also a military component, but the Department of Homeland Security has jurisdiction over Coast Guard operations (in peacetime), not the DoD.

    The Department Of Defense

    In 1789, the United States had a War Department. This is considered a proto-DoD with many of the same concerns and responsibilities. Federal leaders saw a need to unify the military services under a single authority but this would not formally evolve into what we understand today as the DoD until 1947.

    A Secretary of Defense was named, and in 1949 the National Security Act was amended to remove military service secretaries from cabinet-level duties and also to formally rename the National Military Establishment as the Department of Defense, according to Defense.gov.

    In keeping with the Constitutionally-mandated requirement to maintain civilian control of the military, the Secretary of Defense and all service secretaries are civilian posts appointed by the Commander-in-Chief.

    The Service Secretaries include:

    • Army Chief of Staff
    • Air Force Chief of Staff
    • Chief of Naval Operations
    • Commandant of the Marine Corps

    There are four flag-level officers appointed as Joint Chiefs Of Staff nominated by the Commander-in-Chief and approved by the Senate. The Joint Chiefs of Staff report directly to the Secretary of Defense and the President for operational issues.


    The Branches Of Military Service: Army, Navy Air Force, Marine Corps

    Those who want to enlist or get an officer’s commission into the U.S. military have a lot of choices. The Coast Guard, under the auspices of the Department of Homeland Security, has the same recruiting and retention needs as the other services but their recruiting efforts aren’t don’t seem to be as highly visible as the branches of service under the DoD.

    Those who want to join the military have the option to join:

    Those interested in joining the Air Force have the option of asking the recruiter about potential service opportunities with Space Force. At press time, Space Force does not have its own recruiting operations the way the Air Force does. The Air Force official site directs those interest in Space Force opportunities to its main AF recruiting page.

    No matter which branch of service you choose, you may have the opportunity (with the right qualifications) to apply as an officer (degree required) or enlisted member (no college required in most cases). Officers are required to have a college degree and must attend their branch of service’s officer candidate school or equivalent.

    Those who join the Army, Navy, or Marine Corps may have the option to join as a Warrant Officer, which is a rank higher than all enlisted, but lower than any officer including the lowest junior grade officer. Warrant Officers often perform highly specialized duty or serving as a technical expert. Each branch of service still using Warrant Officers have their own educational and service commitment standards for Warrant Officers.

    Joining The Military

    Anyone who joins the military as an enlisted member will be sent to basic training first, then to more advanced training or on-the-job training depending on the career field, and finally to a first assignment stateside or overseas.

    Getting assignments in the military is a complicated process and may depend partly on the luck of the draw, partly on staffing issues, and partly on how many military career fields are understaffed at assignment time.

    No matter what your recruiter might tell you or imply about military assignments, there are literally NO guarantees where you will go, what you will end up doing (within your career field or MOS) once you arrive. Each assignment is unique, and the needs of the branch of service are considered first. Accept that as early as possible for best results.

    Job Assignment Versus Military Duty Assignments

    When you join the military you may have the opportunity to select your career field or MOS before going to the Military Entrance Processing Station (MEPS) to ship out to basic training. If this is offered to you, TAKE IT.

    Get into a guaranteed job that appeals to you as early as possible and avoid shipping out to basic training in “open general” status or without a career field assignment. This is NOT always possible, but if it is, take full advantage.

    Your career field choice will determine how your first tour of duty will go. Those who choose to enter highly skilled career fields such as military linguists may well spend their entire first year in uniform at a technical school learning these skills. Others may be able to leave basic training for a minimum amount of advanced training before being sent to their first assignment.

    And that first assignment is what we mean by “military duty assignment”. In other words, the military base you work at. These assignments are made within each branch of service and those assignments can last anywhere from one year to four years typically.

    TDY Versus PCS

    Some military duty isn’t as long as one year. Any duty that requires you to be away from your assigned military base that is shorter than 180 days is considered temporary duty–you do not fully relocate to perform this duty, you go temporarily.

    This type of duty can include deployments to war zones, military exercises, and more. Any duty that is longer than 180 days generally must count as a military assignment. This might sound like we’re simply assigning definitions to terms like “TDY” or “permanent change of station” or PCS. But the reality is, if you come off a short assignment instead of a TDY, you may be entitled to certain considerations for a new assignment not available for those coming off temporary duty.


    The Branches Of Military Service

    The United States Army

    Described in some circles as the primary ground force of the U.S. military, the Army is much more than just “grunts”. The 21st century soldier has a far more sophisticated level of training, equipment, and understands modern warfare better than any of her counterparts from decades past. The U.S. Army uses helicopters, fixed-wing aircraft, missiles, and much more. The Army is traditionally the backbone of the Department of Defense.

    Army organization includes the active duty force, plus an Army Guard and an Army Reserve.

    The United States Air Force

    The U.S. Air Force started as part of the Army, but after 1947 the Air Force was a separate and equal branch of the military. World War Two proved to military leaders that there was a distinct advantage in maintaining air superiority in any conflict.

    The Air Force, like the Army, uses both fixed-wing and rotor aircraft, but is also responsible for the nation’s nuclear deterrent as well as military satellites. The Air Force includes a Reserve component and a National Guard component.

    The U.S. Space Force, at the time of this writing, is closely associated with the Air Force and all interested in Space Force jobs will need to coordinate with an Air Force recruiter to learn what opportunities are open at application time. Space Force’s role is likely to grow and change over the coming years and today’s guidelines and regulations may be modified later to accommodate a growing role for it.

    The United States Navy

    The U.S. Navy is to the sea what the Air Force is to the sky. The Navy’s job is to protect national security and U.S. interests at sea and elsewhere. Like the Army, the U.S. Navy is not restricted to a certain type of craft; the Navy operates helicopters and fixed-wing aircraft on land and at sea.

    Navy power includes being able to bring a sea-going runway with as many as 80 aircraft at a to a combat operation. The ability to launch and operate combat aircraft where no other runways are available is a major advantage. The Navy also operates a fleet of submarines which provide their own unique, stealthy advantages.

    Unlike the Air Force where you are not guaranteed duty on board aircraft, the recruits who join the U.S. Navy get told right away they should expect to perform sea duty. It may be less common than some think that a sailor could do an entire military career without ever going underway–if you don’t like the water or think the idea of being at sea for months at a time won’t agree with you, don’t assume you can join the Navy and avoid working on board a ship or other vessel.

    Like the Army and Air Force, the Navy is supported by a reserve component, but there is no National Guard branch of the Navy.

    The United States Marines

    The Navy and Marine Corps have a unique relationship because Marines are primarily a combat force; doctors, for example, are supplied by the Navy. There are no Marine surgeons, and Marine Corps operations commonly depend on the Navy supplying such support.

    Marines have more demanding physical standards than other branches of military service, and it’s no surprise why. Marines are known for amphibious operations, self-sustaining ground combat operations and a formidable group of airframes–again, both fixed-wing and rotor aircraft. Past operations have included Marine F-18s and F-35s.

    The U.S. Marine Corps is supported by the Marine Corps Reserve, which is said to the largest organization within USMC.

    Coast Guard

    The Coast Guard is mentioned here because it is a branch of the uniformed services that falls under the DoD in times of war. Said to be the smallest branch of U.S. military service, the Coast Guard started in the late 1700s, and would be re-designated as the Coast Guard in 1915.

    The Coast Guard fell under more than one federal agency in the 20th century but in contemporary times the Department of Homeland Security directs the service in immigration, law enforcement, boating safety, water-based rescues, and public awareness of boating safety. The Coast Guard operates a fleet of boats, ships, and aircraft. The Coast Guard has an Auxiliary of volunteers as well as a Coast Guard Reserve.

    About The AuthorJoe Wallace is a 13-year veteran of the United States Air Force and a former reporter for Air Force Television News

    Written by Veteran.com Team