NEAR KELLY`S FORD, VA., August 8, 1863.

SIR: I have the honor of submitting the following report of the part taken in the action at Gettysburg, Pa., on July 2 and 3, by the Third Brigade: On the morning of July 2, I was informed by Lieutenant Dechert, acting assistant adjutant-general of the brigade, that the command of the division had devolved upon you, and that I was ordered to take the command of the brigade. I immediately took command of the brigade, and, in obedience to orders received from you, I moved it back to the Gettysburg pike, at the point where we had left the same on the day previous, leaving my line of skirmishers engaged with the enemy, and the Twenty-seventh Indiana as a rear guard. Subsequently, according to instructions, I withdrew the line of skirmishers and the Twenty-seventh Indiana. The brigade was then, together with the balance of the division, moved to the front on the hill, forming a part of the line of battle, and then to the right into a piece of woods; and then again to the right, and formed in line on the right of the First Brigade, the One hundred and seventh New York forming the left of the line; the Thirteenth New Jersey formed in double column closed in mass in rear of the One hundred and seventh New York. Immediately on the right of the Thirteenth New Jersey was a small meadow of very low ground, which was considered untenable, and on its right was a small piece of timber, into which I placed the balance of the brigade in the following order: Second Massachusetts, Third Wisconsin, and the Twenty-seventh Indiana on the extreme right of the line. The three last-named regiments occupied three sides of on irregular square. I ordered the One hundred and seventh New York to construct breastworks, their line fronting southeast and forming an angle of about 45 degrees to that of the line occupied by the First Brigade, and completely enfilading the open ground or meadow not covered by our line; the Second Massachusetts fronting to the northeast at nearly the same angle, and also enfilading the open space; the Third Wisconsin fronting to the east, and east, and the Twenty-seventh Indiana to the south. The ground occupied by the two latter regiments was protected in the front by a small creek (Rocky Run) [Rock Creek], some 60 to 80 feet in width and from 6 to 8 feet deep, rendering the position of these two regiments not assailable from the east or south. Breastworks of rails, timber, and stone were speedily thrown up, covering the whole line. In obedience to orders received from you, I subsequently changed the disposition of the regiments. I placed the Third Wisconsin on the left, on that portion of the line occupied by the One hundred and seventh New York; the Thirteenth New Jersey in the position occupied by the Third Wisconsin, and the One hundred and seventh New York in the rear of the three regiments as a reserve. Shortly before sundown, I received information through one of your aides that the extreme left of our line was hard pressed, with orders to immediately proceed with the brigade to the left, to the support of that part of the line. I immediately put the brigade in motion, and proceeded, I should judge, to the left about l 1/2 miles, where the battle appeared to be raging the fiercest. By the time I had gained the point indicated, it had become quite dark. I immediately formed the brigade in line of battle, under your direction, and threw out skirmishers to the front