The United States Army ( USA ) is the largest branch of the United States Armed Forces and performs land-based military operations. It is one of the seven uniformed services of the United States and is designated as the Army of the United States in the United States Constitution, Article 2, Section 2, Clause 1 and United States Code, Title 10, Subtitle B, Chapter 301, Section 3001. As the oldest and most senior branch of the U.S. military in order of precedence,  the modern U.S. Army has its roots in the Continental Army, which was formed (14 June 1775) to fight the American Revolutionary War (1775–1783)—before the United States of America was established as a country. After the Revolutionary War, the Congress of the Confederation created the United States Army on 3 June 1784 to replace the disbanded Continental Army.   The United States Army considers itself descended from the Continental Army, and dates its institutional inception from the origin of that armed force in 1775.
As a uniformed military service, the U.S. Army is part of the Department of the Army, which is one of the three military departments of the Department of Defense. The U.S. Army is headed by a civilian senior appointed civil servant, the Secretary of the Army (SECARMY) and by a chief military officer, the Chief of Staff of the Army (CSA) who is also a member of the Joint Chiefs of Staff. In the fiscal year 2017, the projected end strength for the Regular Army (USA) was 476,000 soldiers ; the Army National Guard (ARNG) had 343,000 soldiers and the United States Army Reserve (USAR) had 199,000 soldiers; the combined-component strength of the U.S. Army was 1,018,000 soldiers.  As a branch of the armed forces, the mission of the U.S. Army is "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".  The branch participates in conflicts worldwide and is the major ground-based offensive and defensive force of the United States.
- Preserving the peace and security and providing for the defense of the United States, the Commonwealths and possessions and any areas occupied by the United States
- Supporting the national policies
- Implementing the national objectives
- Overcoming any nations responsible for aggressive acts that imperil the peace and security of the United States
The Continental Army was created on 14 June 1775 by the Continental Congress  as a unified army for the colonies to fight Great Britain, with George Washington appointed as its commander.    The army was initially led by men who had served in the British Army or colonial militias and who brought much of British military heritage with them. As the Revolutionary War progressed, French aid, resources and military thinking influenced the new army. A number of European soldiers came on their own to help, such as Friedrich Wilhelm von Steuben, who taught Prussian Army tactics and organizational skills.
The army fought numerous pitched battles and in the South in 1780–1781, sometimes used the Fabian strategy and hit-and-run tactics, hitting where the British were weakest to wear down their forces. Washington led victories against the British at Trenton and Princeton, but lost a series of battles in the New York and New Jersey campaign in 1776 and the Philadelphia campaign in 1777. With a decisive victory at Yorktown and the help of the French, the Continental Army prevailed against the British.
After the war, the Continental Army was quickly given land certificates and disbanded in a reflection of the republican distrust of standing armies. State militias became the new nation's sole ground army, with the exception of a regiment to guard the Western Frontier and one battery of artillery guarding West Point's arsenal. However, because of continuing conflict with Native Americans, it was soon realized that it was necessary to field a trained standing army. The Regular Army was at first very small and after General St. Clair's defeat at the Battle of the Wabash, the Regular Army was reorganized as the Legion of the United States, which was established in 1791 and renamed the United States Army in 1796.
Early wars on the Frontier
The War of 1812, the second and last war between the United States and Great Britain, had mixed results. The U.S. Army did not conquer Canada but it did destroy Native American resistance to expansion in the Old Northwest and it validated its independence by stopping two major British invasions in 1814 and 1815. After taking control of Lake Erie in 1813, the U.S. Army seized parts of western Upper Canada, burned York and defeated Tecumseh, which caused his Western Confederacy to collapse. Following U.S.victories in the Canadian province of Upper Canada, British troops who had dubbed the U.S. Army "Regulars, by God!", were able to capture and burn Washington, which was defended by militia, in 1814. The regular army, however proved they were professional and capable of defeating the British army during the invasions of Plattsburgh and Baltimore, prompting British agreement on the previously rejected terms of a status quo ante bellum. Two weeks after a treaty was signed (but not ratified), Andrew Jackson defeated the British in the Battle of New Orleans and Siege of Fort St. Philip, and became a national hero. U.S. troops and sailors captured HMS Cyane, Levant and Penguin in the final engagements of the war. Per the treaty, both sides (the United States and Great Britain) returned to the geographical status quo. Both navies kept the warships they had seized during the conflict.
The army's major campaign against the Indians was fought in Florida against Seminoles. It took long wars (1818–1858) to finally defeat the Seminoles and move them to Oklahoma. The usual strategy in Indian wars was to seize control of the Indians' winter food supply, but that was no use in Florida where there was no winter. The second strategy was to form alliances with other Indian tribes, but that too was useless because the Seminoles had destroyed all the other Indians when they entered Florida in the late eighteenth century.
The U.S. Army fought and won the Mexican–American War (1846–1848), which was a defining event for both countries.  The U.S. victory resulted in acquisition of territory that eventually became all or parts of the states of California, Nevada, Utah, Colorado, Arizona, Wyoming and New Mexico.
American Civil War
The American Civil War was the costliest war for the U.S. in terms of casualties. After most slave states, located in the southern U.S., formed the Confederate States, the Confederate States Army, led by former U.S. Army officers, mobilized a large fraction of Southern white manpower. Forces of the United States (the "Union" or "the North") formed the Union Army, consisting of a small body of regular army units and a large body of volunteer units raised from every state, north and south, except South Carolina. 
For the first two years Confederate forces did well in set battles but lost control of the border states.  The Confederates had the advantage of defending a large territory in an area where disease caused twice as many deaths as combat. The Union pursued a strategy of seizing the coastline, blockading the ports, and taking control of the river systems. By 1863, the Confederacy was being strangled. Its eastern armies fought well, but the western armies were defeated one after another until the Union forces captured New Orleans in 1862 along with the Tennessee River. In the Vicksburg Campaign of 1862–1863, General Ulysses Grant seized the Mississippi River and cut off the Southwest. Grant took command of Union forces in 1864 and after a series of battles with very heavy casualties, he had General Robert E. Lee under siege in Richmond as General William T. Sherman captured Atlanta and marched through Georgia and the Carolinas. The Confederate capital was abandoned in April 1865 and Lee subsequently surrendered his army at Appomattox Court House. All other Confederate armies surrendered within a few months.
The war remains the deadliest conflict in American history, resulting in the deaths of 620,000 soldiers. Based on 1860 census figures, 8% of all white males aged 13 to 43 died in the war, including 6.4% in the North and 18% in the South. 
Later 19th century
Following the Civil War, the U.S. Army had the mission of containing western tribes of Native Americans on the Indian reservations. They set up many forts, and engaged in the last of the American Indian Wars. U.S. Army troops also occupied several Southern states during the Reconstruction Era to protect freedmen.
The key battles of the Spanish–American War of 1898 were fought by the Navy. Using mostly new volunteers, the U.S. Army defeated Spain in land campaigns in Cuba and played the central role in the Philippine–American War.
Starting in 1910, the army began acquiring fixed-wing aircraft.  In 1910, Mexico was having a civil war, peasant rebels fighting government soldiers. The army was deployed to American towns near the border to ensure safety to lives and property. In 1916, Pancho Villa, a major rebel leader, attacked Columbus, New Mexico, prompting a U.S. intervention in Mexico until 7 February 1917. They fought the rebels and the Mexican federal troops until 1918.
The United States joined World War I in 1917 on the side of Britain, France, Russia, Italy and other allies. U.S. troops were sent to the Western Front and were involved in the last offensives that ended the war. With the armistice in November 1918, the army once again decreased its forces.
The United States joined World War II in December 1941 after the Japanese attack on Pearl Harbor. On the European front, U.S. Army troops formed a significant portion of the forces that captured North Africa and Sicily and later fought in Italy. On D-Day 6 June 1944 and in the subsequent liberation of Europe and defeat of Nazi Germany, millions of U.S. Army troops played a central role. In the Pacific War, U.S. Army soldiers participated alongside the United States Marine Corps in capturing the Pacific Islands from Japanese control. Following the Axis surrenders in May (Germany) and August (Japan) of 1945, army troops were deployed to Japan and Germany to occupy the two defeated nations. Two years after World War II, the Army Air Forces separated from the army to become the United States Air Force in September 1947. In 1948, the army was desegregated by order of President Harry S. Truman.
The end of World War II set the stage for the East–West confrontation known as the Cold War. With the outbreak of the Korean War, concerns over the defense of Western Europe rose. Two corps, V and VII, were reactivated under Seventh United States Army in 1950 and American strength in Europe rose from one division to four. Hundreds of thousands of U.S. troops remained stationed in West Germany, with others in Belgium, the Netherlands and the United Kingdom, until the 1990s in anticipation of a possible Soviet attack.  : minute 9:00-10:00
During the Cold War, American troops and their allies fought communist forces in Korea and Vietnam. The Korean War began in 1950, when the Soviets walked out of a U.N. Security Council meeting, removing their possible veto. Under a United Nations umbrella, hundreds of thousands of U.S. troops fought to prevent the takeover of South Korea by North Korea and later to invade the northern nation. After repeated advances and retreats by both sides and the Chinese People's Volunteer Army's entry into the war, the Korean Armistice Agreement returned the peninsula to the status quo in 1953.
The Vietnam War is often regarded as a low point for the U.S. Army due to the use of drafted personnel, the unpopularity of the war with the American public and frustrating restrictions placed on the military by American political leaders. While American forces had been stationed in the Republic of Vietnam since 1959, in intelligence and advising/training roles, they were not deployed in large numbers until 1965, after the Gulf of Tonkin Incident. American forces effectively established and maintained control of the "traditional" battlefield, but they struggled to counter the guerrilla hit and run tactics of the communist Viet Cong and the North Vietnamese Army. On a tactical level, American soldiers (and the U.S. military as a whole) did not lose a sizable battle. 
During the 1960s, the Department of Defense continued to scrutinize the reserve forces and to question the number of divisions and brigades as well as the redundancy of maintaining two reserve components, the Army National Guard and the Army Reserve.  In 1967, Secretary of Defense Robert McNamara decided that 15 combat divisions in the Army National Guard were unnecessary and cut the number to eight divisions (one mechanized infantry, two armored, and five infantry), but increased the number of brigades from seven to 18 (one airborne, one armored, two mechanized infantry and 14 infantry). The loss of the divisions did not sit well with the states. Their objections included the inadequate maneuver element mix for those that remained and the end to the practice of rotating divisional commands among the states that supported them. Under the proposal, the remaining division commanders were to reside in the state of the division base. However, no reduction in total Army National Guard strength was to take place, which convinced the governors to accept the plan. The states reorganized their forces accordingly between 1 December 1967 and 1 May 1968.
The Total Force Policy was adopted by Chief of Staff of the Army General Creighton Abrams in the aftermath of the Vietnam War and involves treating the three components of the army – the Regular Army, the Army National Guard and the Army Reserve as a single force.  Believing that no U.S. President should be able to take the United States (and more specifically the U.S. Army) to war without the support of the American people, General Abrams intertwined the structure of the three components of the army in such a way as to make extended operations impossible, without the involvement of both the Army National Guard and the Army Reserve. 
The 1980s was mostly a decade of reorganization. The army converted to an all-volunteer force with greater emphasis on training and technology. The Goldwater-Nichols Act of 1986 created unified combatant commands bringing the army together with the other four military services under unified, geographically organized command structures. The army also played a role in the invasions of Grenada in 1983 ( Operation Urgent Fury) and Panama in 1989 ( Operation Just Cause).
By 1989 Germany was nearing reunification and the Cold War was coming to a close. Army leadership reacted by starting to plan for a reduction in strength. By November 1989 Pentagon briefers were laying out plans to reduce army end strength by 23%, from 750,000 to 580,000.  A number of incentives such as early retirement were used.
In 1990, Iraq invaded its smaller neighbor, Kuwait, and U.S. land forces quickly deployed to assure the protection of Saudi Arabia. In January 1991 Operation Desert Storm commenced, a U.S.-led coalition which deployed over 500,000 troops, the bulk of them from U.S. Army formations, to drive out Iraqi forces. The campaign ended in total victory, as Western coalition forces routed the Iraqi Army. Some of the largest tank battles in history were fought during the Gulf war. The Battle of Medina Ridge, Battle of Norfolk and the Battle of 73 Easting were tank battles of historical significance.  
After Operation Desert Storm, the army did not see major combat operations for the remainder of the 1990s but did participate in a number of peacekeeping activities. In 1990 the Department of Defense issued guidance for "rebalancing" after a review of the Total Force Policy,  but in 2004, Air War College scholars concluded the guidance would reverse the Total Force Policy which is an "essential ingredient to the successful application of military force." 
On 11 September 2001, 53 Army civilians (47 employees and six contractors) and 22 soldiers were among the 125 victims killed in the Pentagon in a terrorist attack when American Airlines Flight 77 commandeered by five Al-Qaeda hijackers slammed into the western side of the building, as part of the September 11 attacks.  Lieutenant General Timothy Maude was the highest-ranking military official killed at the Pentagon and the most senior U.S. Army officer killed by foreign action since the death of Lieutenant General Simon B. Buckner Jr. on 18 June 1945 in the Battle of Okinawa during World War II. 
In response to the 11 September attacks and as part of the Global War on Terror, U.S. and NATO forces invaded Afghanistan in October 2001, displacing the Taliban government. The U.S. Army also led the combined U.S. and allied invasion of Iraq in 2003. It served as the primary source for ground forces with its ability to sustain short and long-term deployment operations. In the following years, the mission changed from conflict between regular militaries to counterinsurgency, resulting in the deaths of more than 4,000 U.S service members (as of March 2008) and injuries to thousands more.   23,813 insurgents  were killed in Iraq between 2003–2011.
Until 2009, the army's chief modernization plan, its most ambitious since World War II,  was the FCS program. In 2009, many systems were canceled and the remaining were swept into the BCT modernization program.  In response to Budget sequestration in 2013, the army is planned to shrink to a size not seen since the World War II buildup.  From 2016 to 2017, the army retired hundreds of OH-58 Kiowa Warrior observation helicopters without an adequate successor.  The 2015 expenditure for Army research, development and acquisition changed from $32 billion projected in 2012 for FY15 to $21 billion for FY15 expected in 2014.  By 2017, the Brigade Modernization project was completed and its headquarters, the Brigade Modernization Command, was renamed the Joint Modernization Command, or JMC, to reflect its evolving mission at TRADOC.  (TRADOC is the Army Command whose mission is to define the architecture and organization of the Army, to train and supply soldiers to FORSCOM and to design hardware, as well as to define materiel for AMC).  : minutes 2:30-15:00 
The task of organizing the U.S. Army commenced in 1775.  In the first one hundred years of its existence, the United States Army was maintained as a small peacetime force to man permanent forts and perform other non-wartime duties such as engineering and construction works. During times of war, the U.S. Army was augmented by the much larger United States Volunteers which were raised independently by various state governments. States also maintained full-time militias which could also be called into the service of the army.
By the twentieth century, the U.S. Army had mobilized the U.S. Volunteers on four separate occasions during each of the major wars of the nineteenth century. During World War I, the " National Army " was organized to fight the conflict, replacing the concept of U.S. Volunteers.  It was demobilized at the end of World War I, and was replaced by the Regular Army, the Organized Reserve Corps and the State Militias. In the 1920s and 1930s, the "career" soldiers were known as the " Regular Army " with the "Enlisted Reserve Corps" and "Officer Reserve Corps" augmented to fill vacancies when needed. 
In 1941, the " Army of the United States " was founded to fight World War II. The Regular Army, Army of the United States, the National Guard and Officer/Enlisted Reserve Corps (ORC and ERC) existed simultaneously. After World War II, the ORC and ERC were combined into the United States Army Reserve. The Army of the United States was re-established for the Korean War and Vietnam War and was demobilized upon the suspension of the draft. 
Currently, the army is divided into the Regular Army, the Army Reserve and the Army National Guard.  The army is also divided into major branches such as Air Defense Artillery, Infantry, Aviation, Signal Corps, Corps of Engineers, and Armor. Before 1903, members of the National Guard were considered state soldiers unless federalized (i.e., activated) by the President. Since the Militia Act of 1903, all National Guard soldiers have held dual status: as National Guardsmen under the authority of the governor of their state or territory and when activated as a reserve of the U.S. Army under the authority of the President.
Since the adoption of the total force policy, in the aftermath of the Vietnam War, reserve component soldiers have taken a more active role in U.S. military operations. For example, Reserve and Guard units took part in the Gulf War, peacekeeping in Kosovo, Afghanistan and the 2003 invasion of Iraq.
Army commands and army service component commands
|Army Commands||Current commander||Location of headquarters|
Source: U.S. Army organization 
The U.S. Army is made up of three components: the active component, the Regular Army; and two reserve components, the Army National Guard and the Army Reserve. Both reserve components are primarily composed of part-time soldiers who train once a month – known as battle assemblies or unit training assemblies (UTAs) – and conduct two to three weeks of annual training each year. Both the Regular Army and the Army Reserve are organized under Title 10 of the United States Code, while the National Guard is organized under Title 32. While the Army National Guard is organized, trained and equipped as a component of the U.S. Army, when it is not in federal service it is under the command of individual state and territorial governors. However, the District of Columbia National Guard reports to the U.S. President, not the district's mayor, even when not federalized. Any or all of the National Guard can be federalized by presidential order and against the governor's wishes. 
The U.S. Army is led by a civilian Secretary of the Army, who has the statutory authority to conduct all the affairs of the army under the authority, direction and control of the Secretary of Defense.  The Chief of Staff of the Army, who is the highest-ranked military officer in the army, serves as the principal military adviser and executive agent for the Secretary of the Army, i.e., its service chief; and as a member of the Joint Chiefs of Staff, a body composed of the service chiefs from each of the four military services belonging to the Department of Defense who advise the President of the United States, the Secretary of Defense and the National Security Council on operational military matters, under the guidance of the Chairman and Vice Chairman of the Joint Chiefs of Staff.   In 1986, the Goldwater–Nichols Act mandated that operational control of the services follows a chain of command from the President to the Secretary of Defense directly to the unified combatant commanders, who have control of all armed forces units in their geographic or function area of responsibility, thus the secretaries of the military departments (and their respective service chiefs underneath them) only have the responsibility to organize, train and equip their service components. The army provides trained forces to the combatant commanders for use as directed by the Secretary of Defense. 
By 2013, the army shifted to six geographical commands that align with the six geographical unified combatant commands (COCOM):
- United States Army Central headquartered at Shaw Air Force Base, South Carolina
- United States Army North headquartered at Fort Sam Houston, Texas
- United States Army South headquartered at Fort Sam Houston, Texas
- United States Army Europe headquartered at Clay Kaserne, Wiesbaden, Germany
- United States Army Pacific headquartered at Fort Shafter, Hawaii
- United States Army Africa headquartered at Vicenza, Italy
The army also transformed its base unit from divisions to brigades. Division lineage will be retained, but the divisional headquarters will be able to command any brigade, not just brigades that carry their divisional lineage. The central part of this plan is that each brigade will be modular, i.e., all brigades of the same type will be exactly the same and thus any brigade can be commanded by any division. As specified before the 2013 end-strength re-definitions, the three major types of ground combat brigades are:
- Armored brigades, with strength of 4,743 troops as of 2014.
- Stryker brigades, with strength of 4,500 troops as of 2014.
- Infantry brigades, with strength of 4,413 troops as of 2014.
In addition, there are combat support and service support modular brigades. Combat support brigades include aviation (CAB) brigades, which will come in heavy and light varieties, fires (artillery) brigades (now transforms to division artillery) and battlefield surveillance brigades. Combat service support brigades include sustainment brigades and come in several varieties and serve the standard support role in an army.
Combat maneuver organizations
- To track the effects of the 2018 budget cuts, see Transformation of the United States Army#Divisions and Brigades
The U.S. Army currently consists of 10 active divisions and one deployable division headquarters (7th Infantry Division) as well as several independent units. The force is in the process of contracting after several years of growth. In June 2013, the Army announced plans to downsize to 32 active combat brigade teams by 2015 to match a reduction in active duty strength to 490,000 soldiers. Army Chief of Staff Raymond Odierno projected that the Army was to shrink to "450,000 in the active component, 335,000 in the National Guard and 195,000 in U.S. Army Reserve" by 2018.  However, this plan was scrapped by the new administration and now the Army plans to grow by 16,000 soldiers to a total of 476,000 by October 2017. The National Guard and the Army Reserve will see a smaller expansion.  
Within the Army National Guard and United States Army Reserve there are a further 8 divisions, over 15 maneuver brigades, additional combat support and combat service support brigades and independent cavalry, infantry, artillery, aviation, engineer and support battalions. The Army Reserve in particular provides virtually all psychological operations and civil affairs units.
United States Army Forces Command (FORSCOM)
|Direct reporting units||Current commander||Location of headquarters|
|I Corps||LTG Gary J. Volesky||Joint Base Lewis-McChord, Washington|
|Combat maneuver units aligned under FORSCOM|
| ||Fort Bliss, Texas||1 Stryker Brigade Combat Team (BCT), 2 armored BCTs, 1 Division Artillery ( DIVARTY), 1 Combat Aviation Brigade (CAB) and 1 sustainment brigade||III Corps|
|1st Cavalry Division||Fort Hood, Texas||3 armored BCTs, 1 DIVARTY, 1 CAB and 1 sustainment brigade||III Corps|
|Combat maneuver units aligned under other organizations|
|2nd Cavalry Regiment||Rose Barracks, Vilseck, Germany||4 Stryker squadrons, 1 engineer squadron, 1 fires squadron and 1 support squadron||U.S. Army Europe|
|2nd Infantry Division||Camp Red Cloud, South Korea||2 Stryker BCTs, 1 mechanized brigade from the ROK Army,  1 DIVARTY (under administrative control of 7th ID) and 1 sustainment brigade. An ABCT was deactivated and in its place a stateside ABCT from the active divisions is rotated in on a regular basis.||Eighth Army|
|25th Infantry Division||Schofield Barracks, Hawaii||2 infantry BCTs, 1 airborne infantry BCT, 1 Stryker BCT, 1 DIVARTY, 1 CAB and 1 sustainment brigade||U.S. Army Pacific|
|173rd Airborne Brigade Combat Team||Camp Ederle, Vicenza, Italy||3 airborne infantry battalions (including 1st Battalion, 143rd Infantry Regiment of the Texas Army National Guard), 1 airborne field artillery battalion, 1 cavalry squadron, 1 airborne engineer battalion (54th Brigade Engineer Battalion (BEB), effective 17 June 2015)  and 1 airborne support battalion||U.S. Army Europe|
Special operations forces
|Name||Headquarters||Structure and purpose|
|1st Special Forces Command (Airborne)||Fort Bragg, North Carolina||The 1st SFC(A) manages seven special forces groups (the 1st SFG(A), 3rd SFG(A), 5th SFG(A), 7th SFG(A), 10th SFG(A), 19th SFG(A) ( ARNG) and 20th SFG(A) (ARNG)) that are trained for unconventional warfare, foreign internal defense, special reconnaissance, direct action and counter-terrorism missions. The command also manages two military information support groups (the 4th MISG(A) and 8th MISG(A)) that are trained to conduct psychological operations ; the 95th Civil Affairs Brigade (Airborne) that enables military commanders and U.S. ambassadors to improve relationships with various stakeholders via five operational battalions ( 91st CA BN, 92nd CA BN, 96th CA BN, 97th CA BN and 98th CA BN); and the 528th Sustainment Brigade (Airborne) that provides combat service support and combat health support units via a Special Troops Battalion ; the 112th Special Operations Signal Battalion (Airborne), an ARSOF Support Operations Cell, six ARSOF Liaison Elements; and two Medical Role II teams. The command also has an organic Military Intelligence Battalion providing multi-source intelligence information and analysis.|
|Army Special Operations Aviation Command||Ft. Bragg, North Carolina||Organizes, mans, trains, resources and equips Army special operations aviation units to provide responsive, special operations aviation support to Special Operations Forces (SOF) consisting of five units: USASOC Flight Company (UFC), Special Operations Training Battalion (SOATB), Technology Applications Program Office (TAPO), Systems Integration Management Office (SIMO) and the 160th Special Operations Aviation Regiment (160th SOAR)|
|75th Ranger Regiment||Fort Benning, Georgia||Three maneuver battalions (the 1st Ranger BN, 2nd Ranger BN, and 3rd Ranger BN) and a Special Troops Battalion of elite airborne infantry specializing in direct action raids and airfield seizures.|
|John F. Kennedy Special Warfare Center and School||Ft. Bragg, North Carolina||The SWCS selects and trains Army Special Forces, Civil Affairs and Military Information Support Operations Soldiers consisting of five distinct units and one directorate: 1st Special Warfare Training Group (Airborne), Special Warfare Education Group (Airborne), Special Warfare Medical Group (Airborne), Special Forces Warrant Officer Institute, David K. Thuma Noncommissioned Officers Academy and the Directorate of Training and Doctrine.|
|1st Special Forces Operational Detachment-Delta||Ft. Bragg, North Carolina||Elite special operations and counter-terrorism unit under the control of Joint Special Operations Command.|
These are the U.S. Army ranks authorized for use today and their equivalent NATO designations. Although no living officer currently holds the rank of General of the Army, it is still authorized by Congress for use in wartime.
There are several paths to becoming a commissioned officer  including the United States Military Academy, Reserve Officers' Training Corps and Officer Candidate School. Regardless of which road an officer takes, the insignia are the same. Certain professions including physicians, pharmacists, nurses, lawyers and chaplains are commissioned directly into the army and are designated by insignia unique to their staff community.
Most army commissioned officers are promoted based on an "up or out" system. The Defense Officer Personnel Management Act of 1980 establishes rules for timing of promotions and limits the number of officers that can serve at any given time.
Army regulations call for addressing all personnel with the rank of general as "General (last name)" regardless of the number of stars. Likewise, both colonels and lieutenant colonels are addressed as "Colonel (last name)" and first and second lieutenants as "Lieutenant (last name)". 
|US DoD Pay Grade||O-1||O-2||O-3||O-4||O-5||O-6||O-7||O-8||O-9||O-10||O-11|
|Title||SecondLieutenant||FirstLieutenant||Captain||Major||LieutenantColonel||Colonel||BrigadierGeneral||MajorGeneral||LieutenantGeneral||General||General of theArmy|
|Note: General of the Army is reserved for wartime. |
Warrant officers  are single track, specialty officers with subject matter expertise in a particular area. They are initially appointed as warrant officers (in the rank of WO1) by the Secretary of the Army, but receive their commission upon promotion to chief warrant officer two (CW2).
By regulation, warrant officers are addressed as "Mr. (last name)" or "Ms. (last name)" by senior officers and as "sir" or "ma'am" by all enlisted personnel.  However, many personnel address warrant officers as "Chief (last name)" within their units regardless of rank.
|US DoD pay grade||W-1||W-2||W-3||W-4||W-5|
|Title||Warrant Officer 1||Chief Warrant Officer 2||Chief Warrant Officer 3||Chief Warrant Officer 4||Chief Warrant Officer 5|
Sergeants and corporals are referred to as NCOs, short for non-commissioned officers.   This distinguishes corporals from the more numerous specialists who have the same pay grade, but do not exercise leadership responsibilities.
Privates (E1 and E2) and privates first class (E3) are addressed as "Private (last name)", specialists as "Specialist (last name)", corporals as "Corporal (last name)" and sergeants, staff sergeants, sergeants first class and master sergeants all as "Sergeant (last name)". First sergeants are addressed as "First Sergeant (last name)" and sergeants major and command sergeants major are addressed as "Sergeant Major (last name)". 
|US DoD Pay grade||E-1||E-2||E-3||E-4||E-5||E-6||E-7||E-8||E-9|
|Title||Private||Private||PrivateFirst Class||Specialist||Corporal||Sergeant||StaffSergeant||SergeantFirst Class||MasterSergeant||FirstSergeant||SergeantMajor||CommandSergeant Major||Sergeant Majorof the Army|
|Abbreviation||PV1 ¹||PV2 ¹||PFC||SPC ²||CPL||SGT||SSG||SFC||MSG||1SG||SGM||CSM||SMA|
| ¹ PVT is also used as an abbreviation for both private ranks when pay grade need not be distinguished.  |
² SP4 is sometimes encountered instead of SPC for specialist. This is a holdover from when there were additional specialist ranks at pay grades E-5 to E-7.
Training in the U.S. Army is generally divided into two categories – individual and collective. Basic training consists of 10 weeks for most recruits followed by Advanced Individualized Training (AIT) where they receive training for their military occupational specialties (MOS). Some individuals MOSs range anywhere from 14–20 weeks of One Station Unit Training (OSUT), which combines Basic Training and AIT. The length of AIT school varies by the MOS The length of time spent in AIT depends on the MOS of the soldier and some highly technical MOS training may require many months (e.g., foreign language translators). Depending on the needs of the army, Basic Combat Training for combat arms soldiers is conducted at a number of locations, but two of the longest-running are the Armor School and the Infantry School, both at Fort Benning, Georgia.
Following their basic and advanced training at the individual-level, soldiers may choose to continue their training and apply for an "additional skill identifier" (ASI). The ASI allows the army to take a wide-ranging MOS and focus it into a more specific MOS. For example, a combat medic, whose duties are to provide pre-hospital emergency treatment, may receive ASI training to become a cardiovascular specialist, a dialysis specialist or even a licensed practical nurse. For commissioned officers, training includes pre-commissioning training, known as Basic Officer Leader Course A, either at USMA or via ROTC, or by completing OCS. After commissioning, officers undergo branch specific training at the Basic Officer Leaders Course B, (formerly called Officer Basic Course), which varies in time and location according their future assignments. Officers will continue to attend standardized training at different stages of their career.
Collective training at the unit level takes place at the unit's assigned station, but the most intensive training at higher echelons is conducted at the three combat training centers (CTC); the National Training Center (NTC) at Fort Irwin, California, the Joint Readiness Training Center (JRTC) at Fort Polk, Louisiana and the Joint Multinational Training Center (JMRC) at the in Hohenfels, Germany. ARFORGEN is the Army Force Generation process approved in 2006 to meet the need to continuously replenish forces for deployment, at unit level and for other echelons as required by the mission. Individual-level replenishment still requires training at a unit level, which is conducted at the continental U.S. (CONUS) replacement center at Fort Bliss, in New Mexico and Texas before their individual deployment.
- Individual weapons
The army employs various individual weapons to provide light firepower at short ranges. The most common weapons used by the army are the compact variant of the M16 rifle, the M4 carbine,  as well as the 7.62×51mm variant of the FN SCAR for Army Rangers. The primary sidearm in the U.S. Army is the 9 mm M9 pistol ; the M11 pistol is also used. Both handguns are to be replaced by the M17  through the Modular Handgun System program.  Soldiers are also equipped with various hand grenades, such as the M67 fragmentation grenade and M18 smoke grenade.
Many units are supplemented with a variety of specialized weapons, including the M249 SAW (Squad Automatic Weapon), to provide suppressive fire at the squad level.  Indirect fire is provided by the M320 grenade launcher. The M1014 Joint Service Combat Shotgun or the Mossberg 590 Shotgun are used for door breaching and close-quarters combat. The M14EBR is used by designated marksmen. Snipers use the M107 Long Range Sniper Rifle, the M2010 Enhanced Sniper Rifle and the M110 Semi-Automatic Sniper Rifle.
- Crew served weapons
The army employs various crew-served weapons to provide heavy firepower at ranges exceeding that of individual weapons.
The M240 is the U.S. Army's standard Medium Machine Gun.  The M2 heavy machine gun is generally used as a vehicle-mounted machine gun. In the same way, the 40 mm MK 19 grenade machine gun is mainly used by motorized units. 
The U.S. Army uses three types of mortar for indirect fire support when heavier artillery may not be appropriate or available. The smallest of these is the 60 mm M224, normally assigned at the infantry company level.  At the next higher echelon, infantry battalions are typically supported by a section of 81 mm M252 mortars.  The largest mortar in the army's inventory is the 120 mm M120/M121, usually employed by mechanized units. 
The U.S. Army utilizes a variety of direct-fire rockets and missiles to provide infantry with an Anti-Armor Capability. The AT4 is an unguided projectile that can destroy armor and bunkers at ranges up to 500 meters. The FIM-92 Stinger is a shoulder-launched, heat seeking anti-aircraft missile. The FGM-148 Javelin and BGM-71 TOW are anti-tank guided missiles.
U.S. Army doctrine puts a premium on mechanized warfare. It fields the highest vehicle-to-soldier ratio in the world as of 2009. 
The army's most common vehicle is the High Mobility Multipurpose Wheeled Vehicle (HMMWV), commonly called the Humvee, which is capable of serving as a cargo/troop carrier, weapons platform and ambulance, among many other roles.  While they operate a wide variety of combat support vehicles, one of the most common types centers on the family of HEMTT vehicles. The M1A2 Abrams is the army's main battle tank,  while the M2A3 Bradley is the standard infantry fighting vehicle.  Other vehicles include the Stryker,  the M113 armored personnel carrier  and multiple types of Mine Resistant Ambush Protected (MRAP) vehicles.
The Pentagon bought 25,000 MRAP vehicles since 2007 in 25 variants through rapid acquisition with no long-term plans for the platforms. The Army plans to divest 7,456 vehicles and retain 8,585. Of the total number of vehicles the Army is to keep, 5,036 are to be put in storage, 1,073 used for training and the remainder spread across the active force. The Oshkosh M-ATV will be kept the most at 5,681 vehicles, as it is smaller and lighter than other MRAPs for off-road mobility. The other most retained vehicle will be the Navistar MaxxPro Dash with 2,633 vehicles and 301 Maxxpro ambulances. Other MRAPs such as the Cougar, BAE Caiman, and larger MaxxPros will be disposed. 
The U.S. Army's principal artillery weapons are the M109A6 Paladin self-propelled howitzer  and the M270 Multiple Launch Rocket System (MLRS),  both mounted on tracked platforms and assigned to heavy mechanized units.
While the United States Army Aviation Branch operates a few fixed-wing aircraft, it mainly operates several types of rotary-wing aircraft. These include the AH-64 Apache attack helicopter,  the OH-58D Kiowa Warrior armed reconnaissance/light attack helicopter,  the UH-60 Black Hawk utility tactical transport helicopter  and the CH-47 Chinook heavy-lift transport helicopter.  Restructuring plans call for reduction of 750 aircraft and from 7 to 4 types. 
Under the Johnson-McConnell agreement of 1966, the Army agreed to limit its fixed-wing aviation role to administrative mission support (light unarmed aircraft which cannot operate from forward positions). For UAVs, the Army is deploying at least one company of drone MQ-1C Gray Eagles to each Active Army division. 
The Army Combat Uniform (ACU) currently features a digital Universal Camouflage Pattern (UCP) and is designed for use in woodland, desert and urban environments. However, soldiers operating in Afghanistan are being issued a fire-resistant ACU with the " MultiCam " pattern, officially known as Operation Enduring Freedom Camouflage Pattern or "OCP". 
The standard garrison service uniform is the Army Service Uniform, which functions as both a garrison uniform (when worn with a white shirt and necktie) and a dress uniform (when worn with a white shirt and either a necktie for parades or a bow tie for after six p.m. or black tie events).
The U.S. Army's black beret is no longer worn with the new ACU for garrison duty, having been permanently replaced with the patrol cap. After years of complaints that it was not suited well for most work conditions, Army Chief of Staff General Martin Dempsey eliminated it for wear with the ACU in June 2011. Soldiers still wear berets who are currently in a unit in jump status, whether the wearer is parachute-qualified or not (maroon beret). Members of the 75th Ranger Regiment and the Airborne and Ranger Training Brigade (tan beret) and Special Forces (rifle green beret) may wear it with the Army Service Uniform for non-ceremonial functions. Unit commanders may still direct the wear of patrol caps in these units in training environments or motor pools.
The army has relied heavily on tents to provide the various facilities needed while on deployment. The most common tent uses for the military are as temporary barracks (sleeping quarters), DFAC buildings (dining facilities), forward operating bases (FOBs), after action review (AAR), tactical operations center (TOC), morale, welfare and recreation (MWR) facilities, as well as security checkpoints. Furthermore, most of these tents are set up and operated through the support of Natick Soldier Systems Center.
- America's Army ( Video games for recruitment)
- Army CHESS (Computer Hardware Enterprise Software and Solutions)
- Army National Guard
- Comparative military ranks
- History of the United States Army
- List of active United States military aircraft
- List of former United States Army medical units
- List of wars involving the United States
- Military–industrial complex
- Officer Candidate School (United States Army)
- Reserve Officers' Training Corps and Junior Reserve Officers' Training Corps
- Soldier's Creed
- Structure of the United States Army
- Timeline of United States military operations
- Transformation of the United States Army
- U.S. Army Combat Arms Regimental System
- U.S. Army Regimental System
- United States Military Academy
- United States Army Basic Training
- United States Army Center of Military History
- United States Volunteers
- Vehicle markings of the United States military
- Warrant Officer Candidate School (United States Army)