HEADQUARTERS DEPARTMENT OF NEW MEXICO, Fort Craig, N. Mex., March 31, 1862.

Colonel C. CARSON:

COLONEL: You are charged with the duty of holding this post. Your command will consist of seven companies of your own regiment, two of the Second, and one of the Fourth Regiment New Mexico Volunteers. The convalescents, as they become effective, will add to your strength.

I am instructed by the colonel commanding to say that the objects in view and the plan of operations require that it should be held to the last extremity. The manner of doing this is left to your judgment and discretion, in both of which he has the utmost confidence. The force of the enemy in the Mesilla will not allow him to make a regular attack upon the post, but it may be attempted by surprise. To guard against this he desires that you will exercise yourself and exact from all of your command the most unremitting vigilance.

The sick and wounded left in your care will of course receive every attention, and the colonel commanding desires me to say that any expenditures that will add to their comfort or conduce to their recovery will be fully authorized.

Very respectfully, sir, your obedient servant,
WM. J. L. NCODEMUS,

Captain, Twelfth Infantry, Act. Asst. Adjt. General

[APRIL 2, 1862.- For Denver to Halleck, in reference to expedition to New Mexico, see Series I, Vol. VIII, p.653.]

[APRIL 5-6, 1862.-For Halleck to Denver, April 5, and to Sturgis, April 6, in reference, among other matters, to New Mexico expedition, see Series I, Vol. VIII, pp.664,668.]

EXECUTIVE DEPARTMENT, Las Vegas, N. Mex., April 6, 1862.

Hon. W. H. SEWARD,

Secretary of State, Washington City D. C.:

SIR: In my communication of the 30th ultimo I informed you that our forces had fallen back to Bernal Springs, 20 miles from the place of our late encounter with the enemy.

On the day of their arrival at that place the adjutant-general of Colonel Canby, Lieutenant Nicodemus, arrived in camp, bringing news and orders from Colonel Canby. The first was that he had not on the 25th of March left Fort Craig, and the orders were for the whole force to fall back on Union.

These orders were obeyed, and on the 31st ultimo the troops passed this place en route to Fort Union.

Since the late encounter with the enemy we have had occasion to learn much more of the particulars and consequences of that engagement than I could write you in my last communication.

Two days having been given for the burial of the dead and taking