1775-1865
Militia politics, a small regular core, a navy of the early republic, then a mass industrial civil war. Grant is the named closer; the cost band lives on the American Civil War page.
No tactics of 1863 as a lesson to copy.
The United States military is a set of services whose legal modern shape is the National Security Act of 26 July 1947 (Department of Defense, CIA, a separate Air Force) laid over a much older story: 1775 Continental forces, a small nineteenth-century regular army and navy, a mass conscript war in 1861-65, and a global industrial mobilisation in 1941-45. George Washington, Ulysses Grant, and George Marshall are the three English civic names of those scales. This page is era-bounded force-structure history. It is not a live order of battle, not a basing directory, and not a how-to for any arm.
Korea is not a footnote here. 25 June 1950 to the 27 July 1953 armistice was the first large hot war of the 1947 department: MacArthur, then Ridgway; Inchon (15 September 1950); a Chinese intervention; a war that created the US-ROK Mutual Defense Treaty (1 October 1953). Matthew Ridgway is the correction to the MacArthur photograph. The Vietnam War, the all-volunteer force (1973), and the 1986 Goldwater-Nichols jointness law are later hinges. Scale and political impact sit near the top of this atlas because the institution became a global alliance system -- including the ROK.
Anglophone memory is thick to the point of distortion: WWII as "the good war," Korea as the forgotten one, Vietnam as the argument. This file will keep 1950-53 in the second paragraph on purpose. No current ORBAT, no special-operations method, no nuclear employment content (see ICBM).
Origin1775 Continental forces
Mass hingeUS Civil War 1861-65
Global peak1941-45
Legal hingeNational Security Act, 1947
Korea1950-53 as the first hot UN war of the new department
AllianceNATO 1949; US-ROK 1953 mutual defence
Profile
Scale
80
Intensity
55
Duration
74
Tech shift
86
Political impact
88
Cultural memory
78
Deep introduction
A republic that built a department and then an alliance system
The US military's honest twentieth-century sentence is 1947 plus 1950 -- a legal department that went to war on the Korean peninsula before it had finished unpacking.
1917-45
A late entry in WW1; a global mobilisation in WW2. Marshall as the institutional builder; Eisenhower and Nimitz as the two-theatre faces. The bomb is an ICBM-and-WW2 file as well as this one.
No targeting content.
1947-53
A new department, a new air force, NATO (1949), then Korea. MacArthur's relief (11 April 1951) is a civil-military hinge, not a personality show only.
Inchon belongs on its battle page; the alliance belongs here.
1973-86-present as history
All-volunteer force; Goldwater-Nichols; a long post-9/11 period already thick in public files. This page stops at institutional hinges and will not become a current campaign tracker or a SOF manual.
1973-86-present as history stays dated: 1941-45 (Global mobilisation) in A continental republic that became a global basing and alliance system after 1941. Dwight D. Eisenhower (General / president) is a named witness -- Europe's named Supreme Commander and a 1950s president of the alliance age -- including a Korea endgame in 1953 politics. Cost band: not one war -- an institution; human cost sits in the wars this atlas already files. Encyclopedia, not a method.
Seven chapters
01
History
Dated history of United States military (1775 origins; 1861-65 mass army; 1941-45 global peak; 1947 National Security Act as the modern department hinge) in A continental republic that became a global basing and alliance system after 1941.
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02Forces
Historical forces and institutions of United States military -- not a live order of battle.
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03Campaigns
How United States military unfolded as historical sequence, not instruction.
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04Cost
Human and material cost of United States military, as documented ranges.
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05Icons
People and debates around United States military.
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06Legacy
Afterlives and unresolved questions of United States military.
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07Atlas
Maps, portrayals and rituals of United States military.
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Frequently asked questions
When did the modern US Department of Defense begin?
The National Security Act of 26 July 1947 created the department (after a short "National Military Establishment" name) and a separate Air Force. The services are older.
Why is the Civil War notable here?
It was the first US mass industrial army and a cost on the American Civil War page. It is not the origin of the 1947 department.
How does Korea fit?
1950-53 was the first large hot war of that department and produced the 1953 US-ROK treaty. Inchon, Ridgway, and the armistice are dated hinges. See the Korean War and Inchon pages.
What was MacArthur's relief?
President Truman relieved General MacArthur on 11 April 1951 -- a civil-military crisis in a shooting war. A political history, not a staff-college stunt to copy.
Is this a current force list?
No. No live ORBAT, no basing directory, no nuclear employment, no special-operations method.
What was Goldwater-Nichols?
A 1986 law pushing joint service operations -- an institutional reform date in the public file.
How does the ICBM page relate?
The nuclear triad is a US force-structure chapter after 1957. That page holds the type and treaties; this page holds the department that bought them.
Is this a how-to?
No. Encyclopedia of an institution only.