No. 24. report of Col. P. Sidney Post , Fifty-ninth Illinois Infantry, commanding Third brigade, of operations July 27 - August 7 .

Hdqrs. Third Brig., First DIv., 4TH Army Corps, Atlanta, Ga,., September 15, 1864 .

Captain: I have the honor to submit a report of the operations of the Third Brigade, First Division, Fourth Army Corps, while under my command, from the 27th day of July to the 7th of August, 1864 :

The brigade consisted of the following regiments: Eighty-fourth Regiment Illinois Infantry, commanded by Colonel Waters ; Seventyfifth Regiment Illinois Infantry, commanded by Colonel Bennett ; Ninth Regiment Indiana Veteran Infantry, commanded by Colonel Suman ; Seventy-seventh Regiment Pennsylvania Veteran Infantry, commanded by Colonel Rose ; Thirtieth Regiment Indiana Veteran Infantry, commanded by Lieutenant-Colonel Hurd ; Thirty-sixth Regiment Indiana Infantry, commanded by Lieutenant-Colonel Carey ; Fifty-ninth Regiment Illinois Veteran Infantry, commanded by Lieutenant-Colonel Hale ; Eightieth Regiment Illinois Infantry, commanded by Major Stookey . The brigade occupied about threequarters of a mile front in the intrenchments north of Atlanta.

On the 28th day of July , in accordance with orders received, I advanced the right of the skirmish line, consisting of details from all the regiments occupying and permanently holding part of the enemy's rifle-pits, and capturing 3 prisoners. On the 3d day of August , having strengthened the skirmish line with two companies from the Eighty-fourth Regiment Illinois Infantry, I ordered an advance along the whole line, for the purpose of dislodging the enemy from their rifle-pits. This movement was concerted with the brigades on my right and left. The advance was most gallantly made, few shots being fired on our part until the rifle-pits were almost reached, and the enemy had broke and were fleeing. The pioneers were immediately ordered forward, and the rifle-pits were turned against their late occupants. The brigade on our right, which advanced simultaneously as ordered, after reaching the enemy's line was almost immediately driven out and fell back to its original position, while the brigade on the left did not succeed in making any advance; nevertheless, refusing the right and left, we stubbornly held the position gained, and repulsed two attempts of the enemy to retake the work. There being no advantage to be gained by a single brigade holding so advanced a position, Major-General Stanley , commanding the corps, ordered me to withdraw from it, which I accordingly did at night-fall, after the foe had ceased his attempts to retake it, the earth-works having first been leveled and the pits filled up. In this affair we captured 26 prisoners, including 2 commissioned officers, having sustained a loss of but 2 wounded.

In order to distract the enemy's attention from a real attack to be made by the right of our army, on the 5th day of August I again received orders to attack and drive him from his rifle-pits in my front. For this purpose I strengthened the skirmish line with five companies of the Seventy-seventh Pennsylvania Veteran Infantry, under the command of Major Phillips . The artillery along our line opened furiously, and the enemy, evidently suspecting our intentions, were seen to heavily re-enforce their outer line. At the hour designated our skirmishers moved resolutely forward under a galling fire, but without the slightest hesitation or wavering they captured the pits, which they found so near the enemy's main line as to render an attempt to hold them out of the question, and they therefore withdrew at once. In this attack the brigade lost 36 men killed,. wounded, and missing, including Lieutenant Willard , of the Thirtysixth Indiana Infantry, mortally wounded, and that faithful and gallant officer, Captain Walker , of the Seventy-seventh Regiment Pennsylvania Veteran Infantry, who was killed, falling near the enemy's works.

For a list of casualties I refer to the several reports of the regimental commanders.

The rare ability and reliability of the officers commanding the several regiments of this brigade, the exact discipline which they preserved, the soldierly qualities of the men under their command, their ease of combined movement, and esprit de corps, render the duties of a brigade commander but an easy task. I tender my thanks to thte regimental commanders for their cheerful and intelligent co-operation which also made that task for me the greatest pleasure. I commend their meritorious services to the consideration of my superiors and to the gratitude of my countrymen.

The several members of the brigade staff deserve mention for their fearless conduct in the affairs of the 28th of July , the 3d and 5th of August , and for the hearty and efficient assistance rendered me.

I have the honor to be, very respectfully, your obedient servant,

P. Sidney Post, Colonel, Commanding Brigade. Capt. E. D. Mason , Asst. Adjt. Gen., First Div., Fourth Army Corps.