JEFFERSON CITY, September 20, 1861.

I shall leave about 3,000 Home Guards and Iowa Sixth to take care of this place. I would recommend some one of energy be appointed to command them. General Thomas [L.] Price, who is now in Saint Louis, would be an excellent man. They must be kept at work on these field works, &c.

JEFF. C. DAVIS,

Acting Brigadier-General, Commanding.

General JOHN C. FREMONT.

SAINT LOUIS, September 20, 1861.

General JAMES H. LANE:

SIR: It is reported that Lexington is surrounded by an overwhelming rebel force of 16,000, and that our re-enforcements from Utica and Liberty, under command of Brigadier-General Sturgis, are opposite Lexington, and prevented from crossing the river by two rebel batteries. To assist Colonel Mulligan and his brave little band of 2,000, you will harass the enemy as much as possible by sudden attacks upon his flank and rear.

Should Acting Brigadier General Jefferson C. Davis not succeed in effecting a junction with Colonel Mulligan at Lexington he will retreat, and take such a position as haw own strength and the movements and force of the enemy may render advisable. In case the whole rebel force is concentrated around Lexington, he will probably retreat to Davis' Creek, or at farthest ot Dunksburg, at eighter of which places a junction with your forces may be effected. Should the rebels hold Warrensburg with a larger force than that of Acting Brigadier-General Davis, or should he ascertain that McCulloch is also operating towards Lexington, he will take position at Georgetown or Sedalia. You will keep me constantly informed of your own movements and those of the enemy.

J. C. FREMONT,

Major-General, Commanding.

HEADQUARTERS FORT LEAVENWORTH, KANS.,
September 20, 1861.

General JAMES H. LANE,

Commanding Kansas Brigade, West Point, Mo.:

GENERAL: The last reliable information reports Price at Lexington with his whole force, 15,000 to 20,000. He demanded a surrender of the force under Colonel Mulligan, which, as I suppose, is composed of the Irish Brigade and Peabody's command. This demand was ot complied with. A fight ensued without the results desired by the enemy. Re-enforcements are expected at Lexington from the north side of the river. The column under Colonel Smith drove the secessionists to the river opposite the Blue Mills Landing, when a fight ensued. Federal loss reported by telegraph as 50 killed, 25 wounded; the loss of the enemy 150 to 200.

I have this moment received a telegraphic dispatch from General Fremont, dated to-day. He wanted to know your position. I replied, "Last heard from (the 17th) at West Point, marching on Harrisonville." You will readily see the importance of concentrating your force to