William F. Fox, Lt. Col. U. S. V., Regimental Losses in the American Civil War, 1861-1865: A Treatise on the extent and nature of the mortuary losses in the Union regiments, with full and exhaustive statistics compiled from the official records on file in the state military bureaus and at Washington

[65] consisting of five brigades--21 batteries in all. This Artillery Corps of the Army of the Potomac was under command of General Henry J. Hunt.

Prior to the adoption of corps organizations, the various armies of the Union consisted of divisions numbered in the order of their formation. This plan was adhered to in the Western armies until December, 1862. The Army of the Ohio contained several divisions, each division containing three brigades. But these brigades were numbered without reference to their divisions, and hence, in the roster of the Army of Ohio, at Shiloh, we find, for instance, that the Fourth Division--Nelson's — was composed of the 10th, 19th and 22nd Brigades; and at Perryville, in the Eleventh Division--Sheridan's — the brigades were not the 1st, 2d, and 3d, but the 35th, 36th and 37th Brigades. The Army of the Tennessee contained six divisions at Shiloh, and the Army of the Mississippi fought at Iuka without any corps formation. This lack of proper organization did not last long, and in 1863 the Western armies took the field with corps organizations similar to those which General McClellan had instituted in the Army of the Potomac, and which were retained during the remainder of the war.

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First Corps.

• Cedar Mountain
-- Rappahannock -- Gainesville -- Groveton -- Second Bull Run -- South Mountain -- Antietam -- Fredericksburg -- Fitzhugh's Crossing -- Chancellorsville -- Gettysburg -- Mine Run.

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The First Corps, when at its maximum, contained 46 regiments of infantry and 12 batteries of light artillery. It was organized in March, 1862, with three divisions,--King's, McCall's, and Franklin's. General Irwin McDowell was placed in command. When General McClellan moved the Army to the Peninsula, in April, 1862, McDowell's corps was left in Northern Virginia. Franklin's Division was ordered, soon after, to the Peninsula, where it was used in forming the Sixth Corps, its place in McDowell's command being taken by Ricketts' Division. In June, McCall's Division — the famous Pennsylvania Reserves--was also sent to the Peninsular Army, but upon the return of McClellan's forces to Washington, the Reserves rejoined McDowell, and fought under him at Second Bull Run. During the absence of the Army of the Potomac, McDowell was engaged in an active campaign which culminated in the battles around Manassas, the first general engagement in which the corps participated; loss, 595 killed, 2,853 wounded, and 2,021 missing, out of about 18,500 effective men. During the short time in which the army was under Pope, McDowell's Corps was officially designated as the Third Corps, Army of Virginia; but upon General McClellan's restoration to command it resumed its former and proper title,--the First Army Corps.

While on the Maryland campaign the Corps was commanded by General Hooker, and the divisions by Generals Hatch, Ricketts and Meade; it numbered 14,850 men. It was prominently engaged at South Mountain, and also at Antietam, where it opened the battle, its casualties in that engagement amounting to 417 killed, 2,051 wounded and 122 missing. General John F. Reynolds was in command at Fredericksburg, with Doubleday, Gibbon and Meade as division generals; loss, 347 killed, 2,429 wounded, and 561 missing; total, 3,337.

After this battle, the division of Pennsylvania Reserves--Meade's (3d) Division — was withdrawn from the front, and ordered to Washington that it might rest and recruit. This division, in addition to the battles of the First Corps, had served previously on the Peninsula, where it had encountered hard fighting and heavy losses. While on the Peninsula, the Reserves were attached to the Fifth Corps. When the division rejoined McDowell's Corps, at Manassas, it was with depleted ranks which were still further thinned by its subsequent battles. After taking its departure for Washington it never rejoined the First Corps, its