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

At Gettysburg, in the battle of the first day, this corps did some of the best fighting of the war. The division commanders on that field were Wadsworth, Robinson and Doubleday; General Reynolds, who was still in command of the corps, was killed just as he rode on the field, and before his troops were fairly engaged. General Doubleday succeeded to the command, and handled the corps during, that action in a remarkably able. manner. A noteworthy feature of that day was that the corps, although finally driven from the field by a superior force, succeeded in capturing, at different times and at different points on the field, parts of three brigades of the enemy,--Archer's, Davis', and Iverson's¹--taking them in open field fighting, where there were none of the usual accessories of breastworks, intrenchments, or protection of any kind other than that which the field afforded. The First Corps fought that day with no other protection than the flannel blouses that covered their stout hearts. It contained 34 regiments of infantry, and 5 batteries of light artillery, numbering 9,403 infantry “present for duty, equipped;” loss, 593 killed, 3,209 wounded and 2,222 missing; total 6,024, out of less than 9,000 in action. Of the missing, a large proportion were killed or wounded.

Prior to this battle, the roster of the corps had undergone considerable change. Eight New York regiments had gone home, their two years term of service having expired; also, one nine months regiment from Pennsylvania. These changes reduced the First and Second Divisions to two brigades each. The Pennsylvania Reserves had been replaced by a new division of two brigades, to which Stannard's Vermont Brigade was added just before the battle. Stannard's Brigade was composed of nine-months men whose term of service expired just after the battle; three of his regiments took a prominent part in the fighting of the third day, in the repulse of Pickett's charge.

Gen. John Newton, a division general in the Sixth Corps, was appointed to fill Reynolds' place, assuming command during the second day's battle at Gettysburg an appointment which appears as an injustice to Doubleday, who had displayed a marked ability in his operations of the first day. Newton, however, was one of the ablest generals in the service, and was well fitted for so high a command. At Mine Run, his division commanders were Cutler, Robinson, and Kenly. This was the last campaign of the First Corps; for in March, 1864, the organization was ordered discontinued and transferred to the Fifth Corps, the brigades having been consolidated into two divisions, which, under Robinson and Wadsworth, became respectively the Second and Fourth Divisions of the Fifth Corps.

This was an act of gross injustice, and a cruel violation of the corps pride. It was entirely unnecessary; and a serious blunder, instead of an improvement on the army organization.² The men were, however, allowed to wear their old First Corps badges, a concession highly valued, as they had made The little flannel discs synonymous with all that was gallant and grand in war.

The corps had contained some exceptionally good material. The division composed of the Pennsylvania Reserves had no equal in thle Army as a division, while the Iron Brigade was famous for its hard fighting, its percentage of killed exceeding that of any other brigade in the Armies of the Union.

It may be well to note that for a short time, a few weeks only, during Pope's campaign, General Sigel's troops were also officially designated as the First Corps; but, it was the First Corps, Army of Virginia. Then, again, in November, 1864, a few months before the close of the war, the War Department issued orders for the formation of a new corps to be composed of veterans — selected men who had served creditably a full term in their regiments.