Rebellion Record: a Diary of American Events: Documents and Narratives, Volume 7.
Frank Moore, Ed.

About seven o'clock P. M. Major-Gens. Slocum and Sickles, with the Twelfth corps and part of the Third, reached the ground and took post on the right and left of the troops previously posted. Being satisfied, from reports received from the field, that it was the intention of the enemy to support, with his whole army, the attack already made, and reports from Major-Gens. Hancock and Howard on the character of the position being favorable, I determined to give battle at this point, and early in the evening first issued orders to all corps to concentrate at Gettysburgh, directing all trains to be sent to the rear at Westminster at eleven P. M. first.

I broke up my headquarters, which till then had been at Taneytown, and proceeded to the field, arriving there at one A. M. of the second. So soon as it was light I proceeded to inspect the position occupied and to make arrangements for posting several corps as they should reach the ground.

By seven A. M. the Second and Fifth corps, with the rest of the Third, had reached the ground, and were posted as follows: The Eleventh corps retained its position on Cemetery ridge, just opposite to the town ; the First corps was posted on the right; the Eleventh on an elevated knoll connecting with the ridge and extending to the south and east, on which the Twelfth corps was placed, the right of the Twelfth corps resting on a small stream at a point where it crossed the Baltimore pike, and which formed on the right flank of the Twelfth something of an obstacle.

Cemetery ridge extended in a westerly and southerly direction, gradually diminishing in elevation till it came to a very prominent ridge called “Round top,” running east and west. The Second and Third corps were directed to occupy the continuation of Cemetery ridge, on the left of the Eleventh corps and Fifth corps; pending their arrival the Sixth corps was held in reserve. While these dispositions were being made, the enemy was massing his troops on an exterior ridge, distant from the line occupied by us from a mile to a mile and a half.

At two P. M. the Sixth corps arrived, after a march of thirty-two miles, which was accomplished from nine P. M. of the day previous. On its arrival being reported, I immediately directed the Fifth corps to move over to our extreme left, and the Sixth to occupy its place as a reserve for the right.

About three P. M. I rode out to the extreme left to await the arrival of the Fifth corps and post it, when I found that Major-General Sickles, commanding the Third corps, not fully apprehending my instructions in regard to the position to be occupied, had advanced, or rather was in the act of advancing his corps some half-mile or three quarters of a mile in the front of the line of the Second corps on a prolongation which it was designed his corps should rest.

Having found Major-General Sickles, I was explaining to him that he was too far in the advance, and discussing with him the propriety of withdrawing, when the enemy opened upon him with several batteries in his front and his flank, and immediately brought forward columns of infantry, and made a vigorous assault. The Third corps sustained the shock most heroically. Troops from the Second corps were immediately sent by Major-General Hancock to cover the right flank of the Third corps, and soon after the assault commenced.

The Fifth corps most fortunately arrived, and took a position on the left of the Third, Major-General Sykes commanding, immediately sending a force to occupy “Round top” ridge, where a most furious contest was maintained, the enemy making desperate but unsuccessful efforts to secure it. Notwithstanding the stubborn resistance of the Third corps, under Major-General Birney, (Major-General Sickles having been wounded early in the action,) superiority in numbers of corps of the enemy enabling him to outflank its advanced position, General Birney was counselled to fall back and re-form, behind the line originally desired to be held.

In the mean time, perceiving the great exertions of the enemy, the Sixth corps, Major-General Sedgwick, and part of the First corps, to which I had assigned Major-General Newton, particularly Lockwood's Maryland brigade, together with detachments from the Second corps, were all brought up at different periods, and succeeded, together with a gallant resistance of the Fifth corps, in checking and finally repulsing the assault of the enemy, who retired in confusion and disorder about sunset, and ceased any further efforts on our extreme left.

An assault was, however, made about eight P. M. on the Eleventh corps, from the left of the town, which was repelled by the assistance of troops from the Second and First corps. During the heavy assault upon our extreme left, portions of the Twelfth corps were sent as reenforcements.

During their absence the line on the extreme right was held by a very much reduced force. This was taken advantage of by the enemy, who, during the absence of Geary's division of the Twelfth corps, advanced and occupied part of the line.

On the morning of the third July, General Geary having returned during the night, attacked at early dawn the enemy and succeeded in driving him back and reoccupying his former position. A spirited contest was maintained all the morning along this part of the line. General Geary, reenforced by Wheaton's brigade of the Sixth corps, maintained his position and inflicted very severe losses on the enemy.

With this exception, our lines remained undisturbed till one P. M. on the third, when the enemy opened from over one hundred and twenty-five guns, playing upon our centre and left. This cannonade continued for over two hours, when, our guns failing to make any reply, the enemy ceased firing, and soon his masses of infantry become visible, forming for an assault on our left and left centre.