HEADQUARTERS DEFENSES OF THE NEW ORLEANS, July 13, 1863.

Lieutenant-Colonel SAWTELL,
Jefferson Station:

Communicate this act once by express to Lieutenant-Colonel Strickney:

Be very cautious how you advance. There is a report Weitzel has been repulsed on the La Fourche. Hold your force in readiness to fall back on Jefferson Station, leaving the cavalry where you found it.

W. H. EMORY,

Brigadier-General, Commanding.

ENGINEER OFFICE, Port Hudson, July 13, 1863.

Brigadier General CHARLES P. STONE:

GENERAL: With reference to the engineer organization in this department, I have the honor to submit the following report:

These troops, I understand, to be under the immediate command of the chief engineer: Company K, Forty-second Massachusetts (detached), Lieutenant Harding commanding, pontoniers; Company K, Fifty-third Massachusetts (detached), Captain Breman commanding, pioneers; First Louisiana Engineers (colored), Colonel J. Hodge commanding, civil and engineer assistants.

The pontoniers (about 30 men for duty) have a pontoon bridge of about 100 feet, with rigging, &c., complete, in wagons furnished by the quartermaster. They are under orders to join General Weitzel, with 200 feet of bridge, and turn over the rest to Colonel J. Hodge, First Louisiana Engineers. Their time of service expires this week. After the present expedition, I intend to appoint the company of Louisiana Engineers commanded by Captain Smith pontoniers in their stead, and transfer the bridge and train to them.

The prisoners (about 80 men for duty) have about two wagon-loads of tools and materials, forming part of their train of six 4-horse wagons. They are usually kept with the advanced guard for repairing roads, bridges, &c., under the direction of the engineer's assistants. I understand they have proved very useful in this capacity, including many stand they have proved very useful in this capacity, including many mechanics among them. They are at Mount Pleasant Landing, awaiting transportation to join General Grover. I believe their term of service expires in August.

The First Louisiana Engineers (colored) number about 800 men for duty, the colonel reports. They are well supplied with intrenching tools, and have also a fair supply of other engineer materials, such as rope, nails, spikes, chests of tools, &c., for all of which the colonel is responsible, and issues to engineer assistants and general officers on their receipts, by order of the chief engineer. I intend they shall remain here for the present, unless otherwise ordered by Major Houston, and have ordered them to collect all engineer property in the trenches, and then to furnish General Andrews any tools, materials, and working parties he may apply for, till further orders.

The engineer assistants are Captain Long, First Louisiana Engineers, and Sergeant Nutting, Rhode Island Cavalry (detached); 1 surveyor, 2 topographical engineers, and 2 photographers. Captain Long will accompany headquarters, to direct the prisoners in their duties, assisted by Sergeant Nutting. The 2 topographical engineers will also move with