All three components have taken part in every war of the United States from World War I onward. By design, the use of the Army Reserve and National Guard has increased after the Vietnam War. Reserve and Guard units took part in the Gulf War, peacekeeping in Kosovo, and the 2003 invasion of Iraq.
The U.S. Military Academy at West Point, New York commissions its graduates as second lieutenants in the Regular Army. Graduates of other military academies of the United States may elect to be commissioned in the Army
Enlisted soldiers who successfully pass Officer Candidate Schools (OCS)
Lawyers, doctors, nurses, veterinarians, and chaplains may be directly commissioned into their respective corps
Officers receive a commission assigning them to the Officer Corps from the President. All newly commissioned officers receive a commission as a reserve officer. Upon attaining the rank of Major, they can be appointed into the Regular Army with the advice and consent of the United States Senate. Commissioned officers are assigned to a branch of service until they reach the rank of Brigadier General, where it is assumed that they are competent to command soldiers of all branches.
Once commissioned, an officer attends several levels of professional education, starting with branch qualification in their respective branch and concluding in Command and General Staff College at Fort Leavenworth, Kansas. Professional education is required for promotion at certain grades.
The Warrant Officer is a single track specialty officer. Initially appointed an officer by the Secretary of the Army via a warrant, he/she is commissioned by the President upon promotion to the rank of Chief Warrant Officer Two (CW2). The warrant officer is managed as a company grade officer, but receives limited field grade privilege upon promotion to Chief Warrant Officer Four (CW4).
The primary source for Warrant Officers is the U.S. Army Warrant Officer Candidate School at Fort Rucker, Alabama.
The Non-Commissioned Officer Corps (or NCO Corps) is the first line of leadership for the enlisted members of the Army, and includes the ranks of
Corporal (CPL; pay grade E-4) (two stripes up),
Sergeant (SGT; pay grade E-5)(three stripes up),
Staff Sergeant (SSG; pay grade E-6)(three stripes up and one down),
Sergeant First Class (SFC; pay grade E-7) and Platoon Sergeant (PSG; pay grade E-7) (three stripes up and two down),
Master Sergeant (MSG; pay grade E-8) (three stripes up and three down),
First Sergeant (1SG; pay grade E-8) (which holds the same enlisted pay grade as Master Sergeant, but which carries extra administrative duties - three stripes up and three down with a lozenge in the center),
Sergeant Major (SGM; pay grade E-9) (three stripes up and three down with a star in the center),
Command Sergeant Major (CSM; pay grade E-9) (three stripes up and three down with a wreathed star in the center)
and Sergeant Major of the Army (of whom there is only one, and who advises the Chief of Staff of the Army on matters relating to Enlisted personnel - three stripes up and three down with a centered eagle accompanied with two stars).
Training for NCOs takes place at any of the various NCO training centers around the world.
The quality of the NCO has built the reputation of the United States Army. Until relatively recent history, most countries depended upon their officer corps to micromanage strategy, tactics and virtually every other aspect of military operations. With the development of the NCO Corps, the United States Army took a giant step toward utilizing the skills, intelligence, adaptability and independence of its citizens during times of conflict. The confidence and esteem in which the Officer Corps holds the NCOs which serve in the United States Army is based upon hard-won combat experience. This experience has repeatedly shown that rank is no indicator of leadership ability, and that leaders will emerge during times of hardship and conflict.
Private First Class (PFC; pay grade E-3) (one stripe up and a curved stripe (a rocker below),
and Specialist (SPC; pay grade E-4) (which is the same Enlisted Grade as Corporal, but which requires technical leadership skills, as opposed to the combat leadership skills required of corporal -a dark green patch with an eagle centered). A Specialist ranks below a corporal in terms of chain of command.
Training for enlisted soldiers usually consists of Basic Training, and Advanced Individual Training in their primary Military Occupational Specialty (MOS) at any of the numerous MOS training facilities around the world.
All members of the Army must take an oath upon being sworn in as members, swearing (or affirming) to "protect the Constitution of the United States from all enemies, both foreign and domestic." This emphasis on the defense of the United States Constitution illustrates the concern of the framers that the military be subordinate to legitimate civilian authority.
The most senior Army generals who are directly in the chain of command are those who head up the regional joint commands around the world. An example is General John Abazaid, CINCCENTCOM, the Commander-in-Chief Central Command. Three star positions in the Army include some deputy commanders-in-chief of the regional commands, heads of the army sections of those commands, and the general officers commanding of corps.