HEADQUARTERS UNITED STATES FORCES, Donaldsonville, La., July 12, 1863.

Lieutenant Colonel RICHARD B. IRWIN,
Assistant Adjutant-General, Nineteenth Army Corps:

I have the honor to report that I arrived here at 9 p. m. last evening, and my division is now debarked.

Reports from different sources lead to the belief that the enemy are throwing up rifle-pits at Paincourtville; it is thought more for the purpose of retarding our advance than with a view to making a stand.

At Labadieville, however, they are fortifying more strongly, and have three or four 24-pounders in position. The enemy's pickets are within about 2 miles of here, but in no force. The enemy is evidently making preparations to escape if pursued by a strong force, or to resist a small one. Our gunboats can hardly be expected at Brashear City for some days, and it is evidently injudicious to press them until their retreat is cut off. I shall advance guards, and to give us more country from which to obtain forage.

I think it of some little importance to have the Bayou Plaquemine guarded at Indian Village, to prevent guerrilla operations between Plaquemine and here, and also any escape in that direction. A small force with a section of artillery would be sufficient.

I am, colonel, very respectfully, your obedient servant,

C. GROVER,

Brigadier-General, Commanding.

HDQRS. DEFENSES OF NEW ORLEANS, July 12, 1863.

Lieutenant Colonel RICHARD B. IRWIN:

I omitted in my letters to General Banks to mention that when the force interposed between him and myself and this city was threatened, I found it absolutely necessary to have an officer of experience not only in command of the parapet, but also in command of the troops upon the west side of the river.

I therefore appointed Major Houston, chief engineer Department of the Gulf, acting brigadier-general, and placed him in command of the parapet and all the troops and laborers there engaged, and I appointed Captain [Alexander N.] Shipley, quartermaster U. S. Army, acting brigadier-general, and placed him in command of all the troops on the west side of the river, with orders to take up his quarters at the earthworks on the company canal, at which point all the new levies of troops have assembled.

Both these appointments were indispensable to the efficiency of the defense of this city, as things then stood, and the officers are still in the discharge of the duties assigned them.

I hope the appointments will be approved by the general commanding. If they cannot be, no bad consequences an result, but the country will have gained the services of these gentlemen at what threatened to be a very critical period.

I have the honor to be, your obedient servant,
W. H. EMORY,

Brigadier-General, Commanding.

[JULY 12, 1863.-For Banks to Grant, in relation to re-enforcements, see Series I, Vol. XXIV, Part III, p. 504.]