Mississippi regiments, now at Union City, forward to Knoxville to General Zollicoffer, whose command is seriously threatened at that place. If the command of Colonel McCown should be threatened, I shall of course expect you to proceed to his support, with all your forces, if circumstances should require it.

In my dispatch of last night, already alluded to, I expressed the opinion that if the enemy was coming down in the force reported to me it would be expedient for you to cross the river with the whole of your command into Tennessee.

In regard to compliance with this order, you are left to conform your action to the exigencies of the case. I have to repeat that, so soon as the condition of the force in my hands shall be strong enough, I shall with pleasure finish you the troops necessary to proceed with your movement on Missouri. In the mean season I suggest whether it might not be well to take measures for having the plank road out from Point Pleasant put into passable condition. In the condition of uncertainty resting on affairs above, I have stopped the Hill at this place and caused her to discharge a lot of mules and other things she had for you, she being wanted for service in another direction. These things shall be sent forward so soon as you will say you desire them.

I remain, respectfully, your obedient servant,

L. POLK,

Major-General, Commanding P. A. C. S.

NEW MADRID, August 16, 1861.

[General POLK:]

GENERAL: We had no attack last night and nothing occurred after you left. There were two gunboats (nothing else) in the chase of last night; they stopped and lay up against the bank below Island Numbers 10 until about 11 o'clock, and then returned. They had no troops except those necessary to man their guns, and it was simply a chase after the Grampus; failing in overhauling her, they returned. At 2 o'clock last night I received the inclosed communication from Thompson, which explains itself; also the inclosed Extra Republican, from which it is now certain that a battle, and bloody one, has been fought between McCulloch's and Lyon's forces, in which the latter was defeated and Lyon killed. The reports of this battle before were premature (but like Manassas, which was preceded by similar reports), but now it is certain. You will perceive from the Republican that it has thrown everything into commotion. These things explain the statement made by the captain of the captured steamer last night, viz, that the Uncle Sam moved off with a boat load of troops up the river yesterday morning, and that the forces at Norfolk (6 miles below Cairo) were all removed night before last; it explains and confirms the report of Mr. Chew, as given me by General Thompson in his dispatch. In fine, it explains everything, and the various reports through different channels all agree and corroborate and confirm the statements in the Saint Louis Republican. The Granpus went above, saw the gunboats last night, lay up and corroborate and confirm the statements in the Saint Louis Republican. The Grampus went above, saw the gunboats last night, lay up and watched them, and has now gone up to Hickman. I now therefore comprehend all the enemy's movements. His whole force (except 2,000 at Bird's Point) is drawn up to Saint Louis, to save that city and protect his retreating force, crippled and cut to pieces. You will hence perceive the importance of now pressing him from all points by urging our forces forward. The Island Numbers 10 will do the enemy no good without