Rio Grande on January 5, [3,] 1864, Major-General Dana leaving the same day for Point Isabel, to embark for Pass Cavallo. Colonel William McE. Dye, commanding post of Brownsville, and on company of the Twentieth Iowa Infantry, on provost-guard duty, were also relieved by General Dana and taken to some point farther up the coast. The troops now occupying this line are a portion of the Second Division, Thirteenth Army Corps, and their position is as follows: The First Brigade, under Colonel Charles Black, of the Thirty-seventh Illinois, is camped half a mile above the town in a bend of the river, the location being very favorable in every respect; the Second Brigade, under Colonel H. Bertram, Twentieth Wisconsin, is quartered in the town; Colonel Bertram also commanding the post of Brownsville.

The cavalry under command of Colonel E. J. Davis, First Texas Cavalry, are camped 1 1/4 miles above the town, in the second bend of the river, two companies of the First Engineers, Corps de Afrique, and two companies of the Sixteenth Regiment, Corps de Afrique, under Major Hamilton, First Engineers, are camped near the First Brigade, and are working upon the fortifications; six companies of the First Engineers, Corps de Afrique, and eight companies of the Sixteenth Regiment, Corps de Afrique, are camped at Point Isabel, under command of Colonel Hodge, First Engineers; two companies of the First Engineers are camped on Brazos Island.

Before leaving New Orleans, I called upon Major D. C. Houston, chief engineer, Department of the Gulf, for his opinion in regard to the fortifications necessary at Brownsville and at the Brazos; from him I learned that orders had been issued to repair Fort Brown, and to construct certain works at Point Isabel and on Brazos Island. I find that Major-General Dana, after carefully examining the site of Fort Brown and other localities, decided to construct new works at a point three-fourths of a mile above Brownsville in preference to repairing Fort Brown, for the following reasons: That the latter work was not large enough to accommodate the garrison and hold the supplies and public property, should it be necessary, at any time after the main body of this force was moved, to withdraw from the town and occupy the fort when threatened by a superior force, and that the supply of water could readily be cut off from Fort Brown by an enterprising enemy.

The new work situated in the first bend of the river, above Fort Brown, was laid out by Captain A. Hoeppner, and consists of several well-built redoubts, connected by rifle-pits, the works extending across the bend, having a front of 600 yards, and inclosing in the rear at least 100 acres of ground. I consider the site much the best in this neighborhood, and the work infinitely superior in every respect to old Fort Brown. There are three guns in position in this work, two 20-pounder Parrotts and one 24-pounder smooth. Captain Hoeppner, who is now in New Orleans, will furnish a plan of the work, with proper details, to Major Houston. The works at Point Isabel consist of a series of rifle-pits, extending from the light-house to a point on the bay 1,000 yards above, and two small redoubts are also being constructed.

The work on Brazos I have not yet seen, but understand that it is a strong work, facing the sea, and mounting two heavy guns. There are no regular outposts held as such by our troops, occasional scouting parties sent north and northwest answering every purpose, the only organized rebel force west of the Nueces River being that of