20th Corps (McCook's)

Stone's River; Liberty Gap; Chickamauga.

This corps was identical with that part of the Army of the Cumberland, or Fourteenth Corps, which had been designated as the Right Wing until January 9, 1863, when, under General Order No. 9, the War Department directed that the Right Wing be set apart and designated as the Twentieth Corps. Major-General McCook, its former commander, and Generals Davis, Johnson, and Sheridan, its former generals of division, were retained in command.

The troops composing "McCook's Corps," as it was generally called in the army, were veterans who had withstood the fire of hard-fought fields. Many of the regiments had fought at Shiloh, and at Chaplin Hills, and all of them were engaged at Stone's River. McCook had distinguished himself at Shiloh, where his division contributed largely to Buell's success in the second day's battle; also at Chaplin Hills, in which battle his command was almost the only force engaged. The Twentieth Corps, at the time it was so designated, contained the same troops which fought at Stone's River, with the same organization of divisions and brigades. There were three divisions, each containing three brigades; in all, 37 regiments of infantry, and 9 batteries of light artillery, one battery being attached to each brigade. It numbered, just before the battle of Stone's River, 13,779 present for duty.

After Rosecrans' victory at Stone's River, the Twentieth Corps advanced with the Army of the Cumberland and occupied Murfreesboro, where it remained until June, 1863. The advance on Chattanooga then commenced, during which the corps encountered the enemy at Liberty Gap, Tenn., on the 25th of June. Its casualties in that action amounted to 42 killed, 231 wounded, and 1 missing; total, 274.

It accompanied Rosecrans across the Cumberland Mountains in his pursuit of Bragg, and on Sept. 19th fought at Chickamauga. In this battle McCook's Corps took eight brigades, 12,480 men, into action; it lost 423 killed, 2,698 wounded, and 1,215 missing; total, 4,336. One brigade -- Post's (1st) Brigade, Davis' (1st) Division--was not engaged, being absent guarding a supply train.

On September 28th, 1863, the Twentieth and Twenty-first Corps were consolidated, forming the Fourth Corps, Army of the Cumberland. By this arrangement General McCook was left without a command.

Source: "Regimental Losses in the American Civil War (1861-1865)" - William F. Fox

20th Corps (Hooker's)

Rocky Face Ridge; Resaca; Cassville; New Hope Church; Dallas; Pine Knob; Golgotha; Culp's Farm; Kennesaw Mountain; Peach Tree Creek; Siege Of Atlanta; March To The Sea; Siege Of Savannah; Argyle Island; Monteith Swamp; Averasboro; Bentonville; Nashville.

This corps was formed April 4, 1864, by taking the Twelfth Corps, which was composed of the veteran divisions of Williams and Geary, and adding to it Butterfield's newly organized division. At the same time, two divisions of the Eleventh Corps were broken up and distributed to the divisions of Williams, Geary and Butterfield. The badge of the Twelfth Corps was retained, and there was no good reason why its number should not have been retained also; the brigade and division generals of the Twelfth Corps retained their respective commands, and little change was made other than the increase by accessions of transferred material.

Each division now contained three brigades, containing in all 52 regiments of infantry, and 6 batteries of light artillery, numbering 21,280 officers and men present for duty. It was all veteran material, the most of the regiments having served with the Army of the Potomac in many of the greatest battles of the war, and, later on, at Wauhatchie and Lookout Mountain. Major-General Joseph Hooker was placed in command. It was a grand corps, and worthy of the hero who was to lead it.

In addition to the three divisions of Williams, Geary and Butterfield, there was a Fourth Division, under command of Major-General Lovell H. Rousseau. This division was detached on post or garrison duty and never joined the corps; in fact, the men of the Twentieth were unaware of the existence of a Fourth Division. A part of Rousseau's Division was engaged in the Tennessee campaign against Hood, in 1864, and was present at the battle of Nashville.

The Twentieth Corps started, May 4, 1864, on the Atlanta campaign, and during the next four months participated in all the important battles, its hardest fighting occurring at Resaca, May 15th, at New Hope Church, May 25th, and at Peach Tree Creek, July 20th. It was also actively engaged in the investment and siege of Atlanta, sustaining losses daily in killed and wounded while occupying the trenches. During the four months fighting from Chattanooga to Atlanta, it lost over 7,000 men killed, wounded and missing. Before reaching Atlanta, Hooker had a disagreement with Sherman, and asked to be relieved. He was succeeded by Major-General Henry W. Slocum, the former commander of the Twelfth Corps, and one of the ablest generals in the Union armies. General Butterfield, commanding the Third Division, was succeeded during the campaign by General William C. Ward. Upon the evacuation of Atlanta, some troops of the Twentieth Corps--Coburn's Brigade of Ward's Division--were the first to enter and occupy the city, the entire corps remaining there to hold their important prize, while Sherman and the rest of the Army marched in pursuit of Hood.

On November 15, 1864, Sherman and his men started on their grand march through Georgia to the Sea, the Army of the Cumberland--Fourteenth and Twentieth Corps--forming the Right Wing, under command of General Slocum. General A. S. Williams, of the First Division, succeeded to the command of the corps, with Jackson, Geary, and Ward as division generals. When it started on this march, the corps numbered 13,741, present for duty, and contained 47 regiments of infantry, 1 of engineers, 1 of pontoniers, and 4 batteries of light artillery. It was actively engaged at the siege of Savannah, and upon Hardee's evacuation, December 20th, Geary's Division was the first to enter the city.

Leaving Savannah in February, 1865, the Army marched northward through the Carolinas, and at the battle of Averasboro (N. C.), the Twentieth Corps was the only infantry engaged; loss, 77 killed, and 475 wounded. Three days later, Jackson's and Ward's Divisions were hotly engaged in General Slocum's battle at Bentonville. At the close of the campaign, in April, 1865, Major-General Joseph A. Mower was assigned to the command of the corps, whereupon General Williams resumed his old command, that of the First, or Red Star Division.

Williams, whose commission as brigadier dated May 17, 1861, had commanded this division from the beginning of the war. It was remarkable as being the only division which served during the war without a change of commander. Williams commanded it at Winchester, May, 1862, and rode at its head in the Grand Review of May, 1865; he was absent only when in temporary command of the corps. He commanded the Twelfth Corps at Antietam, Mansfield having been killed while going into action; also, at Gettysburg, Slocum being in command then of the Right Wing. He also commanded the Twentieth Corps while on the March to the Sea and through the Carolinas; at the battles of Averasboro and Bentonville. He was an able officer, enjoying to the fullest extent the respect and confidence of every officer and man in his division. Denied the commission of a major-general which he had earned so well, and superseded in command of his corps, the gallant old patriot made no sign of complaint, and continued to serve his country faithfully and well. The persistent refusal to recognize Williams' services together with the influence and motives which prompted such action were discreditable, to say the least.

The campaign in the Carolinas having ended in Johnston's surrender, the Twentieth Corps marched on to Washington, where it participated in the Grand Review, and was then disbanded.

Source: "Regimental Losses in the American Civil War (1861-1865)" - William F. Fox