United States Secretary of the Army in the context of "United States Secretary of War"

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.

The chief of staff of the Army (CSA) is a statutory position in the United States Army held by a general officer. As the highest-ranking officer assigned to serve in the Department of the Army, the chief is the principal military advisor and a deputy to the secretary of the Army. In a separate capacity, the CSA is a member of the Joint Chiefs of Staff (10 U.S.C. § 151) and, thereby, a military advisor to the National Security Council, the secretary of defense, and the president of the United States. The CSA is typically the highest-ranking officer on active duty in the U.S. Army unless the chairman or the vice chairman of the Joint Chiefs of Staff are Army officers.

The chief of staff of the Army is an administrative position based in the Pentagon. While the CSA does not have operational command authority over Army forces proper (which is within the purview of the combatant commanders who report to the secretary of defense), the CSA does exercise supervision of army units and organizations as the designee of the secretary of the Army.

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:

The United States Department of the Army Criminal Investigation Division (CID or DACID), previously known as the United States Army Criminal Investigation Command (USACIDC), is the primary federal law enforcement agency of the United States Department of the Army. Its primary function is to investigate felony crimes and serious violations of military law and the United States Code within the US Army. The division is an independent federal law enforcement agency with investigative autonomy; CID special agents, both military and civilian, report through the CID chain of command to the CID Director, who reports directly to the Under Secretary of the Army and the Secretary of the Army. Unlike their counterparts at OSI and NCIS, Army CID does not have primary counterintelligence responsibilities, as this jurisdiction resides with United States Army Counterintelligence Command (ACI).

USACIDC was established as a United States Army command in 1971 and is headquartered at Marine Corps Base, Quantico, Virginia. Worldwide, the organization has slightly fewer than 3,000 soldiers and civilians, of whom approximately 900 are special agents. The initialism "USACIDC" was used to refer to the Army command itself, while criminal investigation personnel and operations are commonly referred to using the shortened initialism "CID", which has its history in the original Criminal Investigation Division formed during World War I. The name restoration to Criminal Investigation Division became official after 2021 reform.