HEADQUARTERS CAVALRY OUTPOST, Cedar Bayou, Tex., April 16, 1864.

Captain SAMUEL CALDWELL,
Actg. Asst. Adjt. General, Thirteenth Army Corps:

CAPTAIN: I have the honor to report that in obedience to instructions from the major-general commanding I did, on the 14th instant, cross Cedar Bayou onto Saint Joseph's Island with 70 men of my command for the purpose of making a reconnaissance and driving off horses and cattle onto this island. I went as far as the south end of Saint Joseph's Island and communicated with Major Thompson, commanding on Mustang Island. I made a careful inspection of the ground on the south end of the island to ascertain whether the detachment on Mustang Island might not be transferred to a position on this side of Arkansas, equally eligible for commanding (by artillery) that pass, and more eligible for a camp, and am fully of the opinion that it could not. The south and of the island for at least 1 1\2 miles is very low, and in very high tides is covered with water.

This portion of it is also fully and perfectly commanded by the sand-hills on Mustang Island that come up to the water's edge, which hills, if occupied by the enemy, would command the pass. The channel is also near the Mustang side, while on the Saint Joseph's side the water is so shallow that it would be quite impossible for transports to make a landing and discharge their cargoes. In regard to the camp I have the honor to export that there is no eligible position the other side of Arkansas City, with is about 4 miles this side of the extreme point of the island. I found no enemy. I drove off 3 Government mules and 17 ponies, and drove to this end of the island about 1,500 head of cattle. I had made no preparation for swimming the cattle over Cedar Bayou, and owing to the rain that had recently failed could not drive them over the Salt Flats to the reef over which we had to cross, and have left them on this end of the island. I carefully examined the bay side of the island, and think there is no place the enemy can cross except in boats. The land on that side is very flat and boggy. I found about 100 wagon loads of salt on the island. Major Thompson had sent over a small detachment to drive in and butcher cattle for the of rope I could make a good ferry over Cedar Bayou, and if desirable keep up communication with Mustang Island.

I am, captain, respectfully, your obedient servant,

A. C. MATTHEWS,

Major, Commanding.

POST ARANSAS, TEX., April 16, 1864.

Captain SAMUEL CALDWELL,

Acting Assistant Adjutant-General:

CAPTAIN: I have the honor to report that steamer Exact landed here this morning with Company A, Fourteenth Regiment Rhode Island Volunteers Heavy Artillery, and reported as per Special Orders, Numbers 76, in command of Captain T. W. Fry, and will take immediate charge of the guns here. I have communicated with Major Matthews, commanidng camp at Cedar Bayou. All quiet and well.

He spent one night with me here.

12 R R-VOL XXXIV, PT III