Report of Brig. Gen. Mortimer D. Leggett, U. S. Army, commanding First Brigade.
MAY 19-JULY 4, 1863.--The Siege of Vicksburg, Miss.

VICKSBURG, MISS., July 6, 1863.

Maj. R. R. TOWNES,
Assistant Adjutant-General.

        MAJOR: I have the honor to submit the following report of the part taken by the First Brigade, Third Division, Seventeenth Army Corps, consisting of the Twenty-third Indiana Volunteer Infantry, Twentieth, Thirty-first, Forty-fifth, and One hundred and twenty-fourth Illinois Volunteer Infantry, in the siege of Vicksburg, from the 4th of June (the date at which I was assigned to its command) to the 4th of July, 1863, inclusive:
        Until the 25th of June, nothing occurred to call the brigade from its regular routine of (duties--picketing, sharpshooting, and working the trenches being the duties to which it was assigned, and at which it was engaged night and day. By the annexed list of casualties, you will see that I lost only an occasional man while in the discharge of these duties, though during the whole time bivouacked within short musket range of the enemy's works.
        As the trenches progressed, I advanced my sharpshooters, thus protecting as much as possible those at work in the trenches. After running the main trenches up to the enemy's works, I was ordered to withdraw 15 paces and open a sap to the left, running nearly parallel with the enemy's works. The saps and trenches were constructed under the direction of Captain Hickenlooper, of General McPherson's staff. While in the discharge of this duty, a mine was opened at the mouth of the main trench, penetrating the enemy's fort, known as Fort Hill, and on the 25th of June I was ordered to hold my command in readiness to charge and take said Fort Hill as soon as the mine should be sprung, to hold the breach made by the explosion at all hazards, and, if practicable, to charge over and drive the enemy from his works.
        At 3.30 p.m. of said day my command was in readiness, the Forty-fifth Illinois being in the front, supported by the other regiments of the brigade, and Lieut. H. C. Foster, of the Twenty-third Indiana, with 100 men, being placed in the left-hand sap before spoken of, with orders to charge with the Forty-fifth Illinois, provided they attempted to cross the enemy's works. At 4.30 o'clock the mine was sprung, and before the dirt and Smoke was cleared away the Forty-fifth Illinois had filled the gap made by the explosion and were pouring deadly volleys into the enemy. As soon as possible, loop-hole timber was placed upon the works for the sharpshooters, but the enemy opened a piece of artillery at very close range on that point, and the splintering timbers killed and wounded more men than did balls, and I ordered the timbers to be removed. Hand-grenades were then freely used by the enemy, which made sad havoc amongst my men, for, being in the crater of the exploded mine, the sides of which were covered by the men, scarcely a grenade was thrown without doing damage, and in most instances horribly mangling those they happened to strike. The Forty-fifth Illinois, after holding the position and fighting desperately until their guns were too hot for further use, were relieved by the Twentieth Illinois. During this time hand-grenades were freely used on both sides, Private William Lazarus, of Company I, First U.S. Infantry: being detailed to throw them, who, after throwing about twenty, was mortally wounded, after which a detail of 3 men from the same command were detained for that duty. The Twentieth Illinois was relieved by the Thirty-first Illinois, and they in turn by the Fifty-sixth Illinois, of the Third Brigade, but their ammunition being bad they were unable to hold the position, and were relieved by the Twenty-third Indiana. The Seventeenth Iowa, of the Third Brigade, then relieving the Twenty-third Indiana, and the Thirty-first Illinois relieving them, held the position until daylight, when the Forty-fifth Illinois believed them and held the position until 10 a.m. the 28th. The One hundred and twenty-fourth Illinois then relieved the Forty-fifth Illinois, and held the position until 5 p.m. of the same day, when I received orders to withdraw to the left-hand gap, where I maintained the position until the surrender on the 4th of July, when,by order of Major-General Logan, my brigade, led by the Forty-fifth Illinois, was honored with the privilege of being the first to enter the garrison, and the flag of the Forty-fifth the first to float over the conquered city.
        The troops under my command, though for forty-eight days and nights under a harassing fire of musketry and artillery, and constantly subject to duty the most exhausting and fatiguing, bore their part with a courage and patience and persistent energy never excelled.
        I might with justice and truth name many instances of great personal bravery upon the part of officers and men, but I should not know where to stop naming when all did their duty so bravely.
        It is proper, perhaps, that I should especially name Lieut, J. W. Miller, of the Forty-fourth Illinois, who, as one of my staff, was assigned to the immediate command of the pickets and sharpshooters, and in the discharge of this responsible duty was, during the whole siege, in the most exposed position, almost without sleep or rest, exhibiting a personal courage and physical endurance seldom asked for or found in any officer. Inclosed find a tabular list of the killed and wounded. I have the satisfaction of reporting none missing.

Very respectfully,

[Inclosure. ]

Command Killed Wounded Aggregate
20th Illinois 2 7 9
31st Illinios 6 23 29
45th Illinois 7 61 68
124th Illinois 5 47 52
23 Indiana 7 24 31
Total 27 162 189