Report of Colonel Aaron Brown, THIRD Iowa Infantry First, brigade, including operations since May 18.

HEADQUARTERS THIRD IOWA INFANTRY,
July 6, 1863

COLONEL: I have the honor to submit the following report of the action of the THIRD Iowa Infantry on board the steamer Crescent City, May 18, 1863, with guerrillas, and the part taken by it during the siege of Vicksburg:

The regiment left Memphis, Tenn.,. May 17, 1863, in company with the other regiments composing the First Brigade, fourth DIVISION, SIXTEENTH Army Corps. Nothing of interest occurred until about 1 p. m. of the river, near Island Number 82, and about 3 miles above the town of Greeneville, MISS. The Crescent City, on which the regiment was embarked, was at the time about 1 mile in advance of the fleet. The enemy opened on the boat, when within 150 yards of the shore, with three pieces of artillery and a heavy fire of musketry. Two companies, who were on guard at the time, promptly returned the fire, but so sudden and unexpected was the attack, and so short its duration, that the regiment had but a poor opportunity to do much execution until the boat, that got beyond musket range. We had one section of A. Schwartz'[battery on board, one piece of which was used with food effect on the battery on shore. We were at the time under the convoy of one of the boats of the Mosquito fleet,, which came up to our assistance, but not until the enemy were in full retreat. In this affair we lost 14 men wounded, a list of whom you will find appended. On the morning of the 19th, the regiment disembarked at Young's Point, and started toward the interior, but were immediately ordered back to re-embark for Snyder's Bluff, where we landed on the morning of the 20th. Here we remained until the 24th, when we received marching orders, and with the rest of the brigade proceeded to the rear of Vicksburg, and took position on the left of the besieging line, and became part of the investing g force. From this time up to the surrender of the place, on the 4th of July, the regiment took part in all the siege operations carried on in our front. The duty now was of the most arduous character, and calculated to put to the severest test the bravery and fortitude of the men. I shall only instance a few of the most important operations in which the regiment was engaged during the siege.

On the night of the 1st of June, companies F and G were supporting a section of the FIFTH Ohio Battery, wich had been posted early in the evening in an advanced position. The enemy had detected the movement, and about 11 o'clock made a sortie in considerable force to capture the guns and their small support. Our men were on the alert for them, and twice repulse them; the last time when they had got up within 10 feet of the guns, which played havoc in the ranks with canister. On the evening of the 4th, of June, a portion of the regiment on picket duty on the left of the brigade line, crossing of parrots of Companies A, b, d, f, and H, with 20 men and 1 commissioned officer of the Thirty-THIRD Wisconsin Regiment, numbering in all about 150, were ordered to advance and drive the enemy from his line of rifle pits on the crest of a ridge south of the Hall's Ferry road and about 300 yards in our front. At the signal, the men rushed forward with a deafening, cheer, under a heavy fire of musketry and