Organization Of U.S. Forces In The Civil War

        DURING the war the forces called for by the President of the United States were organized first into armies, and later into army corps and armies. The troops sent to a military department were usually called the army of the department in which they operated or were located; the corps were known by numbers, and were part of the army of a department, or sometimes constituted the army.

        The armies of the United States were commanded by

THE PRESIDENT,

as Commander-in-Chief under the Constitutional provision; and under him, as General Commanders, by

BREVET LIEUTENANT-GENERAL WINFIELD SCOTT,

until November 6, 1861.

MAJOR-GENERAL GEORGE B. McCLELLAN,

until March 11, 1862.

MAJOR-GENERAL HENRY W. HALLECK,

from July 11, 1862, to March 12, 1864.

LIEUTENANT-GENERAL and GENERAL U. S. GRANT,

until March 4, 1869.

PRINCIPAL ARMIES OF THE UNITED STATES.

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Army of the Potomac.

        This army was virtually called into existence in July, 1861, and was organized by Major-General George B. McClellan, its first commander; November 5, 1862, Major-General A. E. Burnside took command of it; January 25, 1863, Major-General Joe Hooker was placed in command, and June 27, 1863, Major-General George G. Meade succeeded him.

Army of Virginia.

        General Orders No. 103, War Department, August 12, 1862, directs the forces under Major-Generals Fremont, Banks, and McDowell, including the troops then under Brigadier-General Sturgis at Washington, to be consolidated and called the Army of Virginia, under the command of Major-General John Pope; and in the first part of September, 1862, the troops forming this army were transferred to other organizations, and the army as such discontinued.

Army of the Ohio.

        General Orders No. 97, War Department, November 9, 1861, directed General Don Carlos Buell to assume command of the Department of the Ohio. The troops serving in this department were organized by him as the-Army of the Ohio, General Buell remaining in command until October 30, 1862, when he was succeeded by General W. S. Rosecrans. This Army of the Ohio became, at the same time, the Army of the Cumberland. A new Department of the Ohio having been created, Major-General H. G. Wright was assigned to the command thereof; he was succeeded by Major-General Burnside, who was relieved by Major-General J. G. Foster of the command of the Department and Army. Major-General J. M. Schofield took command January 25, 1864, and January 17, 1865, the Department was merged into the Department of the Cumberland.

Army of the Cumberland.

        The Army of the Ohio, commanded by General Don Carlos Buell, became, October 24, 1862, the Army of the Cumberland, and was placed under the command of Major-General W. S. Rosecrans; it was also organized at the same time as the Fourteenth Corps. In January, 1863, it was divided into three corps, the Fourteenth, Twentieth, and Twenty-first; in September, 1863, the Twentieth and Twenty-first Corps were consolidated into the Fourth Corps. October, 1863, General George H. Thomas took command of the army, and the Eleventh and Twelfth Corps were added to it. In January, 1864, the Eleventh and Twelfth Corps were consolidated and known as the Twentieth Corps.

Army of the Tennessee.

        Originally the Army of the District of Western Tennessee, fighting as such at Shiloh, Tenn., it became the Army of the Tennessee upon the concentration of troops at Pittsburg Landing, under General Halleck; and when the Department of the Tennessee was formed, October 16, 1862, the troops serving therein were placed under the command of Major-General U. S. Grant. October 24, 1862, the troops in this Department were organized as the Thirteenth Corps; December 18, 1862, they were divided into the Thirteenth, Fifteenth, Sixteenth, and Seventeenth Corps. October 27, 1863, Major-General William T. Sherman was appointed to the command of this army; March 12, 1864, Major-General J. B. McPherson succeeded him; July 30, 1864, McPherson having been killed, Major-General O. O. Howard was placed in command, and May 19, 1865, Major-General John A. Logan succeeded him.

        Of the minor armies the following are mentioned in the records in connection with the more important operations:

Army of the Mississippi.

        Operations on the Mississippi River in spring, 1862; before Corinth, Miss., in May, 1862; Iuka and Corinth, Miss., in September and October, 1862.

Army of the Gulf.

        Siege of Port Hudson, La., May, June, and July, 1863.

Army of the James.

        Consisting of the Tenth and Eighteenth Corps and Cavalry, Major-General Butler commanding. Operations in conjunction with Army of the Potomac.

Army of West Virginia.

        At Cloyd's Mountain, May 9 and 10, 1864.

Army of the Middle Military Division.

        At Opequan and Cedar Creek, September and October, 1864.

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ARMY CORPS.

        SECTION 9 of the act approved July 17, 1862, which reads as follows: "And be it further enacted, that the President be and he is hereby authorized, to establish and organize Army Corps according to his discretion"--legalized and allowed the organization of troops into Army Corps, and under this authority the following corps were organized:

First Army Corps.

        August 12, 1862.--The troops of the Mountain Department were to constitute the First Corps, under command of Major-General Fremont.
        April 15, 1863.--Major-General John F. Reynolds assigned to command.
        March 23, 1864.--Discontinued, and troops transferred.
        November 28, 1864.--Reorganized under the command of Major-General Hancock.

Second Army Corps.

        August 12, 1862.--The troops of the Shenandoah Department were to constitute the Second Corps, under command of General Banks.
        September 12, 1862.--The President ordered that this corps should be known hereafter as the Eleventh, and that the corps arranged in General Order No. 101, of March 13, 1862, Headquarters Army of the Potomac, as the Second, should be known as such.
June 28, 1865.--Discontinued.

Third Army Corps.

        August 12, 1862.--The troops under General McDowell, except those within the city and fortifications of Washington, were to form this corps, and to be under his command.
        September 12, 1862.--The President ordered that this corps should be known hereafter as the Twelfth; and that the corps arranged as the Third in General Orders No. 101, of March 13, 1862, Headquarters Army of the Potomac, should be known as such.
        March 23, 1864.--Discontinued, and troops transferred.

Fourth Army Corps.

        September 12, 1862.--The President directed that the corps arranged as the Fourth in General Orders No. 101, of March 13, 1862, Headquarters of the Army of the Potomac, should be known as such. August 1, 1863.--Discontinued, and the troops transferred to other corps.
        September 28, 1863.--The Twentieth and Twenty first Corps consolidated and constituted the Fourth Corps, under command of Major-General Gordon Granger.
        August 1, 1865.--Discontinued.

Fifth Army Corps.

        July 22, 1862.--The President directed that the corps arranged in G. O. No. 125, Headquarters Army of the Potomac, of the forces commanded by Brigadier. General Porter, should be known as the Fifth Corps.
        June 28, 1865.--Discontinued.

Sixth Army Corps.

        July 22, 1862.--The President directed that the corps arranged in G. O. No. 125, Headquarters Army of the Potomac, of the forces commanded by Brigadier-General Franklin, should be known as the Sixth Army Corps.
        June 28, 1865.--Discontinued.

Seventh Army Corps.

        July 22, 1862.--The President directed that the forces under Major-General Dix should constitute the Seventh Corps.
        August 1, 1863.--Discontinued, and the troops transferred to the Eighteenth Corps.
        January 6, 1864.--The troops in the Department of Arkansas to constitute this corps, commanded by Major-General Steele.
        August 1, 1865.--Discontinued.

Eighth Army Corps.

        July 22, 1862.--The President directed that the forces under Major-General Wool should constitute the Eighth Corps.
        March 12, 1863.--Major General Lewis Wallace, commanding Middle Department, assigned to command.
        July 11, 1864.--Major-General E. O. C. Ord assigned to command of the corps, and of all the troops in the Middle Department.
        July 28, 1864.--Major-General Wallace resumed command of the corps, and all the other troops in the Middle Department.
        August 1, 1865.--Discontinued.

Ninth Army Corps.

        July 22, 1862.--The President directed that the troops under Major-General Burnside, and belonging to the Department of North Carolina, should be known as the Ninth Corps.
        July 27, 1865.--Discontinued.

Tenth Army Corps.

        September 3, 1862.--It was ordered that the forces in the Department of the South should constitute the Tenth Army Corps, to be commanded by Major-General O. M. Mitchell.
        December 3, 1864.--Discontinued.
        March 27, 1865.--Reorganized of all troops in the North Carolina not belonging to the Second, Ninth, and Twenty-third Corps and General Sherman's army, with Major-General A. H. Terry in command.
        August 1, 1865.--Discontinued.

Eleventh Army Corps.

        September 12, 1862.--The troops of the Shenandoah Department, commanded by Major-General Banks, were constituted this corps.
        April 4, 1864.--Consolidated with the Twelfth, and constituted the Twentieth Corps.

Twelfth Army Corps.

        September 12, 1862.--The troops under General McDowell, with some exceptions, were constituted this corps.
        April 4, 1864.--Consolidated with the Eleventh, and constituted the Twentieth Corps.

Thirteenth Army Corps.

        October 24, 1862.--The troops under command of Major-General Grant, commanding Department of the Tennessee, were to constitute this corps.
        December 18, 1862.--Major-General J. A. McClernand assigned to the command of the Thirteenth Corps, and the forces under General Grant organized into the Thirteenth, Fifteenth, Sixteenth, and Seventeenth Corps.
        June 11, 1864.--Temporarily discontinued, and troops transferred.
        February 15, 1865.--Reorganized, and Major-General Gordon Granger placed in command.
        July 20, 1865.--Discontinued.

Fourteenth Army Corps.

        October 24, 1862.--The troops under Major-General Rosecrans, commanding the Department of the Cumberland, were ordered to constitute this corps.
        January 9, 1863.--This corps divided into three corps: the Fourteenth, Twentieth, and Twenty-first; the Fourteenth to be commanded by Major-General G. H. Thomas.
        August 1, 1865.--Discontinued.

Fifteenth Army Corps.

        Constituted December 18, 1862, from troops of General Grant's command, and Major-General W. T. Sherman assigned to its command.
        August 1, 1865.--Discontinued.

Sixteenth Army Corps.

        Constituted December 18, 1862, from troops of General Grant's command, and Major-General S. A. Hurlbut assigned to its command.
        November 7, 1864.--The Corps organization abolished.
        February 18, 1865.--Reorganized, and Major-General A. J. Smith in command.
        July 20, 1865.--Discontinued.

Seventeenth Army Corps.

        Constituted December 18, 1862, from troops of General Grant's command, and Major-General J. B. McPherson assigned to command.
        August 1, 1865.--Discontinued.

Eighteenth Army Corps.

        December 24, 1862.--The President ordered that the troops in North Carolina should constitute the Eighteenth Army Corps, and assigned Major-General J. G. Foster to the command.
        August 1, 1863.--The Seventh Army Corps transferred to this corps.
        July 17, 1864.--The troops of the Department of North Carolina and Virginia serving with the Army of the Potomac in the field, to constitute this corps, and Major-General William F. Smith assigned to command.
        December 3, 1864.--Discontinued.

Nineteenth Army Corps.

        January 5, 1863.--Ordered that the troops in the Department of the Gulf shall constitute this corps, to be commanded by Major-General N. P. Banks.
        July 11, 1864.--Major-General Gilmore assigned to temporary command of the part of the corps in the Department of Washington.
        July 13, 1864.--Brigadier-General W. H. Emory placed in command of this portion of the corps.
        November 7, 1864.--Brevet Major-General Emory appointed to command; headquarters with the army of Sheridan, in the field. The organization in the Military Division of West Mississippi known as the Nineteenth Corps, abolished.
        March 20, 1865.--Discontinued.

Twentieth Army Corps.

        January 9, 1863.--The Army of the Cumberland divided into three corps: the Fourteenth, Twentieth, and Twenty-first. The Twentieth to be commanded by Major General A. McD. McCook.
        September 28, 1863.--Consolidated with the Twenty-first, and constituted the Fourth Corps.
        April 4, 1864.--Re-formed of the Eleventh and Twelfth Corps by consolidation, and Major-General J. Hooker placed in command.
        June 1, 1865.--Discontinued.

Twenty-first Army Corps.

        January 9, 1863.--The Army of the Cumberland, divided into three corps, the Fourteenth, Twentieth, and Twenty-first; the latter to be commanded by Major-General T. L. Crittenden.
        September 28, 1863.--Consolidated with the Twentieth, and constituted the Fourth Corps. No badge adopted.

Twenty-second Army Corps.

        February 2, 1863.--The troops in the Department of Washington to constitute this Corps, under command of Major-General Heintzelman.

Twenty-third Army Corps.

        April 27, 1863.--The troops in Kentucky, not belonging to the Ninth Corps, were constituted the Twenty-third Corps, commanded by Major-General G. L. Hartsuff; by Major-General Stoneman, from Jan. 28, 1864; by Major-Gen. Schofield, from April 4, 1864; by Maj.-Gen. J. D. Cox, from Mar. 27, 1865.
        June 8, 1863.--The troops within the Department of the Ohio, not belonging to the Ninth Corps, were to form this corps.
        August 1, 1865.--Discontinued.

Twenty-fourth Army Corps.

        December 3, 1864.--The white infantry of the Tenth and Eighteenth Corps with the Army of the James consolidated and constituted this corps, under the command of Major General E. O. C. Orr.
        August 1, 1865.--Discontinued.

Twenty-fifth Army Corps.

        December 3, 1864.--The colored troops of the Department of Virginia and North Carolina were organized into a corps and constituted the Twenty-fifth, Major-General G. Weitzel commanding.
        January 8, 1866.--Discontinued.

Cavalry Corps, Army of the Potomac.

        April 15, 1863.--Major-General George Stoneman was assigned to the command of this corps, consisting of the cavalry of the Army of the Potomac.
        April 4, 1864.--Major-General P. H. Sheridan was assigned to command.

Source: "Statistical Record of the Armies of the U.S."  By  Frederick Phisterer

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