Chief of Staff of the United States Army in the context of "U.S. Army Air Forces"

The United States Army Corps of Engineers (USACE) is the military engineering branch of the United States Army. A direct reporting unit (DRU), it has three primary mission areas: Engineer Regiment, military construction, and civil works. USACE has 37,000 civilian and military personnel, making it one of the world's largest public engineering, design, and construction management agencies. The USACE workforce is approximately 97% civilian, 3% active duty military. The civilian workforce is mainly located in the United States, Europe and in select Middle East office locations. Civilians do not function as active duty military and are not required to be in active war and combat zones; however, volunteer (with pay) opportunities do exist for civilians to do so.

The day-to-day activities of the three mission areas are administered by a lieutenant general known as the chief of engineers/commanding general. The chief of engineers commands the Engineer Regiment, comprising combat engineer, rescue, construction, dive, and other specialty units, and answers directly to the chief of staff of the Army. Combat engineers, sometimes called sappers, form an integral part of the Army's combined arms team and are found in all Army service components: Regular Army, National Guard, and Army Reserve. Their duties are to breach obstacles; construct fighting positions, fixed/floating bridges, and obstacles and defensive positions; place and detonate explosives; conduct route clearance operations; emplace and detect landmines; and fight as provisional infantry when required. For the military construction mission, the chief of engineers is directed and supervised by the Assistant Secretary of the Army for installations, environment, and energy, whom the President appoints and the Senate confirms. Military construction relates to construction on military bases and worldwide installations.

The United States Army (U.S. Army) is the land service branch of the United States Armed Forces. It is designated as the Army of the United States in the United States Constitution. It operates under the authority, direction, and control of the United States secretary of defense. As a part of the United States Department of Defense, it is one of the six armed forces of the United States and one of the eight uniformed services of the United States. The Army is the most senior branch in order of precedence amongst the armed services. It has its roots in the Continental Army, formed on 14 June 1775 to fight against the British for independence during the American Revolutionary War (1775–1783). 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 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 a member of the Joint Chiefs of Staff. It is the largest military branch, and in the fiscal year 2022, the projected end strength for the Regular Army (USA) was 480,893 soldiers; the Army National Guard (ARNG) had 336,129 soldiers and the U.S. Army Reserve (USAR) had 188,703 soldiers; the combined-component strength of the U.S. Army was 1,005,725 soldiers. The Army's mission 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 of America.‌

The Department of the Army (DA) is one of the three military departments within the United States Department of Defense. The DA is the federal government agency within which the United States Army (U.S.) is organized. It is led by the secretary of the Army, a civilian official appointed by the president and confirmed by the Senate. The highest-ranking military officer in the department is the chief of staff of the Army, who is also a member of the Joint Chiefs of Staff. Other senior officials of the department are the under secretary of the Army (principal deputy to the secretary) and the vice chief of staff of the Army (principal deputy to the chief of staff.)

The DA is a successor to the Department of War which was originally formed in 1789 as an Executive Department of the United States. The Department of War was split by the National Security Act of 1947 into the Department of the Army and Department of the Air Force on September 18, 1947.

Dwight David "Ike" Eisenhower (born David Dwight Eisenhower; October 14, 1890 – March 28, 1969) was the 34th president of the United States, serving from 1953 to 1961. During World War II, he was Supreme Commander of the Allied Expeditionary Force in Europe and achieved the five-star rank as General of the Army. Eisenhower planned and supervised two of the most consequential military campaigns of World War II: Operation Torch in the North Africa campaign in 1942–1943 and the invasion of Normandy in 1944.

Eisenhower was born in Denison, Texas, and raised in Abilene, Kansas. His family had a strong religious background, and his mother became a Jehovah's Witness. Eisenhower, however, belonged to no organized church until 1952. He graduated from West Point in 1915 and later married Mamie Doud, with whom he had two sons. During World War I, he was denied a request to serve in Europe and instead commanded a unit that trained tank crews. Between the wars he served in staff positions in the US and the Philippines, reaching the rank of brigadier general shortly before the entry of the US into World War II in 1941. After further promotion Eisenhower oversaw the Allied invasions of North Africa and Sicily before supervising the invasions of France and Germany. After the war ended in Europe, he served as military governor of the American-occupied zone of Germany (1945), Army Chief of Staff (1945–1948), president of Columbia University (1948–1953), and as the first supreme commander of NATO (1951–1952).

Douglas MacArthur (26 January 1880 – 5 April 1964) was an American general who served as a top commander during World War II and the Korean War, achieving the rank of General of the Army. He served with distinction in World War I; as chief of staff of the United States Army from 1930 to 1935; as Supreme Commander, Southwest Pacific Area, from 1942 to 1945 during WWII; as Supreme Commander for the Allied Powers overseeing the occupation of Japan from 1945 to 1951; and as head of the United Nations Command in the Korean War from 1950 to 1951. MacArthur was nominated for the Medal of Honor three times, and awarded it for his WWII service in the Philippines. He is one of only five people to hold the rank of General of the Army, and the only person to hold the rank of Field Marshal in the Philippine Army.

MacArthur, the son of Medal of Honor recipient Arthur MacArthur Jr., was raised on Army posts in the Old West. He was valedictorian of the West Texas Military Academy, and First Captain at the U.S. Military Academy at West Point, where he graduated first in his class in 1903. During the 1914 U.S. occupation of Veracruz, he conducted a reconnaissance mission for which he was nominated for the Medal of Honor. In 1917, he was promoted from major to colonel and became chief of staff of the 42nd (Rainbow) Division. On the Western Front during World War I, he rose to the rank of brigadier general, was again nominated for a Medal of Honor, and was awarded the Distinguished Service Cross twice and the Silver Star seven times. From 1919 to 1922, MacArthur served as Superintendent of the U.S. Military Academy, where he initiated a series of reforms. His next posting was in the Philippines, where in 1924 he was instrumental in quelling the Philippine Scout Mutiny. In 1925, MacArthur became the Army's youngest major general at the age of 45, and in 1930 was appointed Chief of Staff of the U.S. Army. He was involved in the controversial expulsion of the Bonus Army protesters in Washington, D.C., in 1932, and organized the Civilian Conservation Corps. In 1935, MacArthur was appointed Military Advisor to the Commonwealth of the Philippines. He retired from the Army in 1937, but continued as an advisor and as a Field Marshal in the Philippine Army from 1936.

Matthew Bunker Ridgway (3 March 1895 – 26 July 1993) was a senior officer in the United States Army, who served as Supreme Allied Commander Europe (1952–1953) and the 19th Chief of Staff of the United States Army (1953–1955). Although he saw no combat service in World War I, he was intensively involved in World War II, where he was the first Commanding General (CG) of the 82nd Airborne Division, leading it in action in Sicily, Italy and Normandy, before taking command of the newly formed XVIII Airborne Corps in August 1944. He held the latter post until the end of the war in mid-1945, commanding the corps in the Battle of the Bulge, Operation Varsity and the Western Allied invasion of Germany.

Ridgway held several major commands after World War II and is most well-known for resurrecting the United Nations (UN) war effort during the Korean War. Several historians have credited Ridgway for turning the war around in favor of the UN side. He also persuaded President Dwight D. Eisenhower to refrain from direct military intervention in the First Indochina War to support French colonial forces, thereby essentially delaying the United States' Vietnam War by over a decade. He received the Presidential Medal of Freedom on 12 May 1986. Ridgway died in 1993 at the age of 98.

The Army Service Forces was one of the three autonomous components of the United States Army during World War II, the others being the Army Air Forces and Army Ground Forces, created on 9 March 1942. By dividing the Army into three large commands, the Chief of Staff, General George C. Marshall, drastically reduced the number of officers and agencies reporting directly to him. The Army Service Forces brought together elements of five different components of the Army: elements of the War Department General Staff (WDGS), especially its G-4 division (responsible for logistics); the Office of the Under Secretary of War; the eight administrative bureaus; the nine corps areas, which became service commands; and the six supply arms and services, which became known as the technical services. The Army Service Forces was initially known as the United States Army Services of Supply but the name was changed on 12 March 1943, as it was felt that the term "supply" did not accurately describe the broad range of its activities. The Army Service Forces was abolished on 11 June 1946 and most of its functions were taken over by the War Department General Staff.

For most of its existence, the Army Service Forces was commanded by General Brehon B. Somervell, with Lieutenant General Wilhelm D. Styer as his chief of staff. After Styer left for the Pacific, he was succeeded by Major General LeRoy Lutes on 18 April 1945. Brigadier General Lucius D. Clay was the Deputy Chief of Staff for Requirements and Resources, and as such he was responsible for the development of the Army Supply Program, the operation of the Lend-Lease program, and liaison with the War Production Board concerning the allocation of raw materials. Although he had his own logistics staff in the G-4 division of the War Department General Staff, it was to Somervell and Styer that Marshall turned to for advice on logistical matters, and it was Somervell who attended the important wartime conferences.

The Joint Chiefs of Staff (JCS) is the body of the most senior uniformed leaders within the United States Department of Defense, which advises the president of the United States, the secretary of defense, the Homeland Security Council and the National Security Council on military matters. The composition of the Joint Chiefs of Staff is defined by statute and consists of a chairman, a vice chairman, the chiefs of the Army, Marine Corps, Navy, Air Force, and Space Force, and the chief of the National Guard Bureau. Each of the individual service chiefs, outside their Joint Chiefs obligations, works directly under the secretaries of their respective military departments, e.g. the secretary of the Army, the secretary of the Navy, and the secretary of the Air Force.

Following the Goldwater–Nichols Act in 1986, the Joint Chiefs of Staff do not have operational command authority, either individually or collectively, as the chain of command goes from the president to the secretary of defense, and from the secretary to the regional combatant commanders. Goldwater–Nichols also created the office of vice chairman, and the chairman is now designated as the principal military adviser to the secretary of defense, the Homeland Security Council, the National Security Council and the president.

The United States under secretary of the Army is the second-highest-ranking civilian official of the United States Department of the Army, serving directly under the secretary of the Army. The secretary and under secretary, together with two military officers, the chief of staff and the vice chief of staff of the Army, constitute the senior leaders of the United States Army.

The following officials report to the under secretary of the Army: