On the 20th of June, General Beauregard, commanding the "army of the Potomac," headquarters at Manassas Junction, organized his army into six brigades, the First commanded by Bonham, composed of the regiments of Gregg, Kershaw, Bacon and Cash. Sloan's regiment was assigned to the Sixth brigade, Early's; and Jenkins' regiment to the Third, Gen. D. R. Jones. Col. N. G. Evans, an officer of the old United States army, having arrived at Manassas, was assigned to command of a temporary brigade--Sloan's Fourth South Carolina, Wheat's Louisiana battalion, two companies Virginia cavalry, and four 6-pounder guns.
On the 11th of July, General Beauregard wrote to the President that the enemy was concentrating in his front at Falls church, with a force of not less than 35,000 men, and that to oppose him he had only about half that number. On the 17th, Bonham's brigade, stationed at Fairfax, met the first aggressive movement of General McDowell's army, and was attacked early in the morning. By General Beauregard's orders Bonham retired through Centreville, and took the position assigned him behind Mitchell's ford, on Bull run. The Confederate army was in position behind Bull run, extending from Union Mills ford on the right to the stone bridge on the left, a distance of 5 miles.
The brigades were stationed, from right to left, as follows: Ewell, D. R. Jones, Longstreet, Bonham, Cocke, and Evans on the extreme left. Early was in reserve, in rear of the right. To each brigade a section or a battery of artillery was attached, except in the case of Bonham who had two batteries and six companies of cavalry attached to his command. Seven other cavalry companies were distributed among the other brigades. Bonham's position was behind Mitchell's ford, with his four regiments of Carolinians; Jenkins' Fifth regiment was with General Jones' brigade, behind McLean's ford, and Sloan's Fourth regiment was with Evans' brigade on the left, at the stone bridge. With this disposition of his little army, General Beauregard awaited the development of the enemy's movement against him.
At noon on the 18th, Bonham at Mitchell's ford and Longstreet at Blackburn's ford, were attacked with infantry and artillery, and both attacks were repulsed. General McDowell was engaged on the 19th and 20th in reconnoitering the Confederate position, and made no decided indication of his ultimate purpose. The delay was golden for the Confederates. Important reinforcements arrived on the 20th and on the morning of the 21st, which were chiefly to fight and win the battle, while the main body of Beauregard's army held the line of Bull run. General Holmes, from the lower Potomac, came with over 1,200 infantry, six guns and a fine company of cavalry; Colonel Hampton, with the infantry of his legion, 600 strong, and the Thirteenth Mississippi; Gen. Joseph E. Johnston, from the Shenandoah, with Jackson's, Bee's and Bartow's brigades, 300 of Stuart's cavalry and two batteries, Imboden's and Pendleton's.