HEADQUARTERS DEPARTMENT OF THE CULF, New Orleans, La., February 25, 1864.

Major General JOHN A. McCLERNAND,
Commanding Thirteenth Army Corps, New Orleans:

GENERAL: Your letter of yesterday's date, covering letter from Major-General Dana of 15th instant, is this day received, and has been submitted to the major-general commanding, who instructs me to desire you to inform General Dana that he is not, and has not been, expected to hold positions on the mainland of Texas, or to operate against the enemy in the interior whit his insufficient force. He is expected to hold Pass Cavallo securely, and the force at his command is sufficient, if properly entrenched, for that purpose. To place the occupation of that important position beyond question in security, you will please instruct General Dana to withdraw from Indianola the force now there, and not to attempt to hold any position on the mainland, until such time as he shall be sufficiently re-enforced to fully justify it. A small force of cavalry for picket duty was ordered yesterday to Pass Cavallo to report to Major-General Dana.

Very respectfully, I am, general, your most obedient servant,

CHAS. P. STONE,

Brigadier-General, Chief of Staff.

HEADQUARTERS THIRTEENTH ARMY CORPS, New Orleans, La., February 25, 1864.

Lieutenant Colonel R. B. IRWIN,
Asst. Adjt. General, Department of the Gulf:

COLONEL: Your communication of yesterday, calling my attention to the fact that the tri-monthly report of this command for the 10th instant fails to account for the entire corps, has been very seriously considered. Upon examining the files and records at these headquarters in order to correct the errors pointed out by you, and to prevent their recurrence, I find that the Thirteenth Army Corps as originally constituted is much disorganized. To illustrate this I transmit herewith a tabular statement of its organization on the 31st of August, 1863, and of its present organization, so far as I can understand it. The cavalry of the corps was separated from it by special Orders, Numbers 230, from department headquarters, dated September 15, 1863, and appears to have been dropped from our reports since that time. The Sixteenth Regiment Indiana Infantry and the Eighty-seventh and One hundred and eighteenth Regiments Illinois Infantry, all mounted, have also been dropped.

It would seem that the rest of the corps has been reported regularly and with as much precision as was attainable by its different commanders. That portion of the First Division (General Warren) stationed at Plaquemine and Baton Rouge has never been reported to these headquarters since it was sent there, although no order separating it from the corps can be found. Only partial and irregular reports have been received from the Third Division (General McGinnis) since December last. The First U. S. Infantry ceased to report to its proper headquarters in October, 1863. The Ninety-seventh Regiment Illinois Infantry, of the Second Brigade, Fourth Division, has also failed to report since October, 1863. The Ninety-seventh Regiment Illinois Infantry, of the Second Brigade, Fourth Division, has also failed to report since October, 1863. The reports