Numbers 21.

Report of Colonel John B. Sanborn, Fourth Minnesota Infantry, commanding First Brigade.

HDQRS. FIRST Brigadier, THIRD DIV., ARMY OF THE MISS.,
September 21, 1862.

SIR: I have the honor to report that, in pursuance of your orders of the 17th instant, I moved my command, consisting of the Fifth Iowa Infantry, Twenty-sixth Missouri Infantry, Forty-eighth Indiana Infantry, Fourth Minnesota Infantry, Sixteenth Iowa Infantry, and Eleventh Ohio Battery, at 4 a. m., in an easterly direction, to a point on the Tuscumbia road 1 mile west of the junction of the Potomac road with the same without meeting with any opposition. At this point I disposed of my command in order of battle and posted a strong guard on my front and flanks and awaited further orders. In pursuance of your order of 2 a. m. of the 19th instant I moved my command in an easterly direction on the Tuscumbia road, proceeded by the Third Michigan Cavalry. When I had advanced abut 3 miles I fell upon the enemy's pickets, who fired briskly at the advanced cavalry and retired across a clearing into a thick growth of timber and brush, and continued their fire as the cavalry advanced so rapidly that it was deemed prudent to have a portion of the cavalry dismount and advance as infantry skirmishers. It being desirable at this time to conceal from the enemy all our force except the cavalry, I advanced in this manner to the point where the read leading from Iuka to Bay Springs crosses the Tuscumbia road and halted, disposing of my command in the best manner possible, in my judgment, to receive an attack from any quarter,a nd posted guards south, east, and north. I had hardly accomplished this when I received your further orders to move forward immediately toward Iuka. I at once drew in my guards and took up my line of march on the Iuka road, preceded, as before, by cavalry. When i had advanced abut 2 miles the firing of the enemy's pickets was so rapid and well sustained that, under your orders, I threw out four companies of the Fifth Iowa Infantry as skirmishers. These companies moved forward to their task with great alacrity, and soon succeeded in driving the enemy's pieces from a strong position they had selected in a house by the road-side and advanced steadily, driving them for three hours, killing two of them and seriously wounding one at least. At this time (about 4 p. m.) I relieved the companies skirmishing from the fifth Iowa by four companies of the Twenty-sixth Missouri Infantry, who went forward with the greatest cheerfulness, and continued to drive in the enemy's pickets rapidly till they reached a point a little more than a mile from Iuka, where they met the enemy, drawn up in line of battle, in strong force (about 18,000 infantry, with cavalry and artillery) and drew the fire from nearly his whole line. The enemy almost instantaneously opened his batteries upon us and commenced advancing his line, and rendered the most rapid movements and formation necessary to prevent him enveloping my whole command. I immediately caused the Fifth Iowa to file to the right of the road and form in order of battle, with the right wing slightly refused, to prevent it, as far as possible, from being flanked on that wing before other troops could be brought up. The Eleventh Ohio Battery was brought into position immediately on the left of this regiment, the Forty-eighth Indiana Infantry on its left, with the left wing slightly refused, and the Fourth Minnesota in the prolongation of this line. This line was on the crest of a ridge.