Why so many armies?

[Manassas 1861]

Why did the ACW have so many armies. You have the Army of Northern Virginia, Army of Tennessee, Army of the Potomac, why did both sides have multiple armies if they are all part of the same military force?

 

[Piedone]

It is just to facilitate organization.

 

[RedRover]

An army was defined as follows from H.L. Scott's 1863 "military dictionary."

The US Constitution, Article I, section 8, gives to Congress the power to raise and support "armies..."

These armies to be organized in whatever manner the Congress determines by laws. For example, during the war there was the regular army of the United States, there was the Volunteer force (the majority), there was the United States Colored Troops, a Veterans Reserve Corps, etc., and there were large forces of militia at different times placed in the actual service of the United States as such (like the 300,000 9-month militia called forth in 1862-63).
All of these armies were under the command of the President of the United States.

From Article 2, Section 2, the President the commander-in-chief of the army and navy of the United States, and of the militia in the actual service of the United States.

The President's lawful powers were managed through the War Department, under the Secretary of War, which organized the armies into territorial/departmental and field forces commands.



During the war both sides established territorial military departments, in which a senior officer commanded. Some of these military departments had very few troops at all. Others had enough to form separate field armies, like the "Army of the Ohio," in the Department of the Ohio, or the "Army of the Cumberland" in the Department of the Cumberland.

These departmental commands and their boundaries were frequently modified by combination or separation as necessary. For example, in 1863 the Departments and armies of the Ohio, Tennessee, and Cumberland were combined into the "Military Division of the Mississippi" under General Sherman...

General Grant noted in 1864 that only the Union's Army of the Potomac was free-standing, or unconnected with a departmental command.

The field armies were principally composed of two or more army corps.


During 1863 the United States gave permanent and free-standing designations to the various corps in the several armies.

This prevented confusion, for example, between say the 1st Corps, Army of the Tennessee, and 1st Corps, Army of the Potomac. Thenceforward each corps, nation-wide, would have a permanent numerical designation, no matter to what army it was assigned.

In Sherman's force in 1864, the Armies of the Tennessee and Cumberland had two or three army corps each. The smaller Army of the Ohio had only a single corps (the 23rd), besides its army headquarters and attached units. It if were necessary, all three of the armies under Sherman could have moved and operated independently of each other.

 

[thomas aagaard]

Why did the ACW have so many armies. You have the Army of Northern Virginia, Army of Tennessee, Army of the Potomac, why did both sides have multiple armies if they are all part of the same military force?

organization and geography.
It make very little sense for a general near Washington, to be commanding a army in the west so the two sides split their force up into multiply armeis.

Civil War Army Organization

The American Battlefield Trust's educational webpage describing the structure and evolution of Civil War armies.

www.battlefields.org

 

[Fairfield]

It makes sense. The ACW wasn't a single front war nor was it limited to single campaigns. However each side had a secretary of war and a general-in-chief for oversight and co-ordination.

IMO (keeping in mind that the level of my military expertise is mighty low) multiple armies was an advantage to the Union because the telegraph provided the central command (if I may use that term) with almost immediate updates whereas it hindered the Confederates because of the obstruction of individual generals whose sole focus was limited to their own army.

 

[RedRover]

IMO (keeping in mind that the level of my military expertise is mighty low) multiple armies was an advantage to the Union because the telegraph provided the central command (if I may use that term) with almost immediate updates whereas it hindered the Confederates because of the obstruction of individual generals whose sole focus was limited to their own army.

The Confederates used telegraphic communication too. And frequently made strategic redeployments of troops by rail. Like Longstreet's corps at Chickamauga. Just had less resources and manpower to move around.

Somewhat like you mention the Confederates did not empower a real General-in-Chief in the manner of General Grant, until January, 1865, when the Confederate Congress established the position as intermediary between the CS Armies and President Davis. General Lee was saddled with this post, though there was little he could do considering his continued direct management of the Army of Northern Virginia and condition of the Confederacy (soon to be overwhelmed).

The armies in the field all had a base of supply, ultimately related to their department. The Confederates loss of territory affected them in this. For example, the Department and Army of Tennessee, was maneuvered out of Tennessee in the summer of 1863, and over the next year fought principally in Georgia, etc. The resources of which were needed to supply the troops in Virginia.

When General Joe Johnston was placed in command of the Army of Tennesee (in Georgia) in early 1864, he complained of certain inefficiencies in the supply system...

Jefferson Davis responded that getting the army into fighting order, and launching an offensive to retake Tennessee was the best means of ensuring the supplies necessary...

The larger the armies, the larger the necessary concentrations of supplies to keep them in the field, and the Confederate army always struggled to feed its armies more or less.

 

[Saphroneth]

Functionally speaking it's because the term "army" is overloaded. "Army" refers both to a coherent body of troops in the field under a single commander and also to the total land combat force working for a single nation. It was also used for organizational purposes to designate the units under a given commander.


Once you disambiguate, it's fairly simple - a single commander can generally only be in one place at a time, cloning technology not being very advanced in the Civil War days, and so it would be impossible for the same field commander to operate forces in southern Virginia and also in the Shenandoah Valley.


Since "Army" was an organizational concept as well as a term for a field force, this sometimes led to a single "army" which had multiple field forces as part of it or, more commonly, a single field force that was composed of elements from multiple "armies". A good example of the latter is Pope's force in August 1862, which contained the Army of Virginia and the Army of the Potomac (organizational terms) but was a single force under Pope's command.

 

[Sheltowee]

Continues today-

• United States Army Centralheadquartered at Shaw Air Force Base, South Carolina
• United States Army Northheadquartered at Fort Sam Houston, Texas
• United States Army Southheadquartered at Fort Sam Houston, Texas
• United States Army Europe and Africa headquartered at Clay Kaserne, Wiesbaden, Germany
• United States Army Pacificheadquartered at Fort Shafter, Hawaii

 

[Stryker65]

Continues today-

• United States Army Centralheadquartered at Shaw Air Force Base, South Carolina
• United States Army Northheadquartered at Fort Sam Houston, Texas
• United States Army Southheadquartered at Fort Sam Houston, Texas
• United States Army Europe and Africa headquartered at Clay Kaserne, Wiesbaden, Germany
• United States Army Pacificheadquartered at Fort Shafter, Hawaii

Yes. We still have corps as well, XVIII Airborne being one of the most famous. Additionally, "Military Divisions" of Civil War time have now become "Commands" of modern times, such as CENTCOM, SOCOM, etc.

 

[Saphroneth]

The basic summary is that English as a language has not furnished us with different terms for "army" (in the sense of a field force), "Army" (in the sense of an organizational category larger than the corps) and "army" in the sense of the whole land military force of a nation.

Then again, nobody really seems to have those terms as distinct.

 

[Josh The Lighthouse Guy]

In the 20th century the term "army group" or "front" were often used for theater commands or sections of a long battlefront. Even with vastly improved communications since the 1860s the distance and quantity of men necessitated organizational levels above corps.

Union army names often corresponded with the Department. So Rosecrans commanded the Department of the Cumberland, whose field formation was the Army of the Cumberland, which he also commanded.

 

[Bentonville]

If you look right after the war started troops from west Mississippi, Missouri, Arkansas were the army of the Mississippi. When they got to Tennessee they were re-Christened the AoT.
Might add to confusion on the down south end.

 

[Saphroneth]

In the 20th century the term "army group" or "front" were often used for theater commands or sections of a long battlefront. Even with vastly improved communications since the 1860s the distance and quantity of men necessitated organizational levels above corps.

And even then, an "Army Group" was generally composed of multiple "Armies". It's a terminological confusion that seems hard to get away from.

 

[GELongstreet]

Beside the well-known principal field armies there were numerous smaller forces designated as armies, for at least a while, at times merely division-strength. The occasional synonymous use of the term for the forces in a department or location without regard for the actual size didn't make things clearer.

 

[Saphroneth]

So far as I'm concerned, the real issue is that there's a maximum size an army can be, but there's not really a minimum size. A geographically designated army like "The Army of the Potomac" or "The Army of the Frontiers" or "The Army of the Alps" essentially means a force which is under unitary command and which has a general area of operations - or, for political and esprit-de-corps reasons, it can mean a force from there which has moved elsewhere.

Sherman commands a force of multiple "Armies" in 1864 because the components of his force are drawn from all over the West. There's been no big renaming of the Army of the Ohio, Army of the Cumberland and Army of the Tennessee - all originally geographical designations - because to re-designate one of those forces into something else was not a priority.
In practice since Sherman was in command of a field force within the size commonly accepted as being possible for an army, that was under unitary command, he was commanding one army that was split up in odd ways. We could rename the components of his force as "corps" without it looking ridiculous.

 

[7thWisconsin]

You know where President Lincoln kept his armies, right?
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In his sleevies!

 

[Stryker65]

You know where President Lincoln kept his armies, right?
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In his sleevies!

Oh God no...

 

[Josh The Lighthouse Guy]

In practice since Sherman was in command of a field force within the size commonly accepted as being possible for an army, that was under unitary command, he was commanding one army that was split up in odd ways. We could rename the components of his force as "corps" without it looking ridiculous.

The components of Sherman's forces were already organized into corps.

But yes the existing corps could have been part of a single army, especially if Cumberland and Tennessee were designated Wings.

Interestingly, Sherman kept the multiple army organization for the March to the Sea, even though 2 of the 3 armies he took to Atlanta had been officially broken up. (Thomas at Nashville more or less had the de facto Army of the Cumberland, but it was no longer designated as such.)

 

[Saphroneth]

The components of Sherman's forces were already organized into corps.

I mean partly in the sense of size. Sherman's army numbers about a hundred to a hundred and ten thousand troops, plus-minus, and has about 24 divisions in seven infantry corps (totalling about 90,000-100,000) plus cavalry.

We wouldn't exactly bat an eye if his forces consisted of three or four corps at that size - it's not all that much bigger than Lee's three-corps army at Gettysburg.

 

[Stryker65]

Another major point worth considering is the fact that "armies" were often designated as "corps", especially in late 1862. For example, the Army of the Tennessee was originally designated Thirteenth Corps, with fourteen divisions divided into wings; the Army of the Cumberland was originally designated Fourteenth Corps, with thirteen divisions also divided into wings.

The number of divisions definitely got too confusing, which is why the Army structure was created with the subordinate corps. However, the numbering system continued for the divisions, at least until the middle of 1863. For example, at Vicksburg, McClernand's 13th Army Corps consisted of the 9th, 10th, 12th, and 14th Divisions, and McPherson's 17th consisted of the 3rd, 6th, and 7th Divisions. At Stones River, the Army of the Cumberland was still known as Fourteenth Corps, and most of the divisions had only recently changed numbering systems.