be countermanded. Said instructions contemplate that Major Lugenbeel should remain until the construction of the post is completed or in readiness for occupation. On account of the large number of desertions (owing to the tempting proximity to the mines), I anticipate that he will find it difficult to complete the post this fal, and his services there until next spring will be extremely valuable. Your instructions of 19th of May said that, in the event of your finding it impracticable to procure forage in sufficient quantities for cavalry designed to garrison Fort Boise during the coming winter, you will in the fall withdraw such portions of that force as you may deem necessary to winter at Fort Walla Walla. The commanding officer at Fort Walla Walla was some time since notified, a ccordingly that the three companies of First Oregon Cavalry under Colonel Maury, of that r egiment, now in the field, will winter there, and that timely supplies of forage, &c., should be provided. Special Orders, Numbers 58, of the 29th of May, from these headquarters, provided for the return of that command to Fort Walla Walla, and my detqiled instrutins of the 29th of May to Colonel R. F. Maury (a copy of which has been forwarded to you) say that "your command will not return to Fort Boise before the 1st of October, and the cavalry, with Company H, First Washington Territory Infantry, will return to Fort Walla Walla about the 26th of October. " I did not think it advisable that Colonel Maury should return to Fort Boise before October 1, in order that he may remain out uponthe emigrant road up to the latest practicable date to protect the extreme rear of the emigration. In making such arrangements \to protect the emigration in an efficient manner, I never forgot the premature return, early in September, 1860, of Major Grier to Fort Walla Walla, and of the sad massacre which subsequently occurred. I am satisfied that the sad massacre which subsequently occurred. I am satisfied tht Fort Boise will have as much as they can do to cut hay sufficeient to winter the mules they will detain, and that the cavalry ought to return. I may wish to leave a detachment of twenty- five cavalry, under Lieutenant Hobart, at that post- the same detachment which accompanied Major Lugenbeel in his march. In recommending that my arrangements for Colonel Maury to winter at Fort Walla Walla shall remain undisturbed, it is but just to say that he started int the field with full understanding of such an arrnagemertn, unless it might become desirable ere close of witner to send him to Fort Lapwai. To stay out with his command on the emigrant road until 1st of October, after that date to repair to Fort Walla Walla and remove to Fort Boise, cannot well be done before winter. The largest portion of his regiment must winter at Fort Walla Walla, and would there be properly under his immediate supervision. It has been with regret that I have found that the public service required that the headuqarters of the First Washington Territory Infantry and the First Oregon Cavalry should be for awhile at the same post, but wevents seem to have so shaped themselves that for the present it seems unavoidable.

I have the honor to be, very respectfully, your obedient servant,

BENJ. ALVORD,

Brigadier-General, U. S. Volunteers, Commanding District.

HEADUQARTERS DEISTRICT OF ARIZONA,

Las Cruces, N. Mex., August 5, 1863.

Major WILLIAM McCLEAVE,

Commanding Detachment California Volunteers, Fort Thorn:

MAJOR: From your advices I have decided to unite your force with Captain Shirland's, with a view to operating against the Indians south