NEW ORLEANS, October 6, 1864.

(Received 12th.)

Major General C. C. WASHBURN,

Memphis:

Your dispatch of September 28, is received. I think that General Sherman is able to take care of any force in his rear,but I will relieve your cavalry now in Arkansas at the earliest possible moment, and will detach some from Vicksburg if it can be spared.

E. R. S. CANBY,

Major- General.

HEADQUARTERS,
Saint Louis, Mo, October 6, 1864- 3.40 p. m.

(Received 930 p. m.)

Major-General HALLECK,

Chief of Staff:

The delay of reports of affairs here through division headquarters will make a brief report of military affairs here. Until Price attacked Pilot Knob we were uncertain whether he would not come by Rolla, sending Shelby by the Knob. Since then we have been doing everything to concentrate at Jefferson City, Rolla, and Saint Louis. Here the citizen exempts have organized some 6,000 men, who are armed. General Smith covered this place from Price with one division, until the latter crossed the Ozark into the Meramec. Ewing, with about 1,000 men and a battery of six field pieces, evacuated Pilot Knob on the 27th, and, pursued by two divisions of rebel cavalry, made good his retreat to Rolla, losing only a few stragglers and the killed and wounded left at the Knob, the enemy's loss will not fall much short of a thousand hors de combat. Price is now advancing on Jefferson City,where we have now nearly 8,000 men. General Mower reached Girardeau last night, and will be up to- morrow. General Smith is at Gray's Summit, with his troops and 3,00 militia, waiting the arrival of General Mower. All of our cavalry force not at Jefferson City,and about 700 in North missouri, is with General Smith. It greatly crippled us that the Missouri State Militia Cavalry was not supplied with horses during the summer. Only one- half or two- thirds of the for e is effectively mounted. North Missouri is quiet, except along the river counties and the railroad lines, where robbers and guerrillas are at work terribly,in spite of all we can do.

W. S. ROSECRANS,

Major- General.

FORT LEAVENWORTH, October 6, 1864- 11.30 a. m.

Major- General ROSECRANS,

Saint Louis:

General Brown telegraphs that McNeil and Sanborn have joined him at Jefferson City. Reports of enemy advancing to attack but not yet seen. General Fisk had previously arrived. What news ave you as to Price's movements! I desire to regulate mine to suit his.

S. R. CURTIS,

Major-General.