It is 11 o'clock. Beauregard has become satisfied that his orders for the Rebel advance and attack on Centreville, have failed or miscarried. His plan is abandoned, and the orders countermanded. At the same time the growing volume of artillery-detonations upon the left of the Bull Run line of defense--together with the clouds of dust which indicate the route of march of Hunter's and Heintzelman's Divisions from near Centreville to the point of conflict, satisfies both Johnston and Beauregard, that a serious attack is imperilling the Rebel left. Beauregard at once proposes to Johnston "a modification of the abandoned plan," viz.: "to attack with the" Rebel "right, while the left stands on the defensive." But rapidly transpiring events conspire to make even the modified plan impracticable. Johnston, convinced by the still growing volume of battle-sounds on the Rebel left, that the main attack of McDowell is being made there, urges Beauregard to strengthen the left, as much as possible; and, after that general has sent orders to this end,--to Holmes and Early to come up with their Brigades from Union Mills Ford, moving "with all speed to the sound of the firing," and to Bonham to promptly send up, from Mitchell's Ford, a battery and two of his regiments--both he and Beauregard put spurs to their horses, and gallop at full speed toward the firing, four miles away on their left,--stopping on the way only long enough for Johnston to order his Chief-of-artillery, Colonel Pendleton, to "follow, with his own, and Alburtis's Batteries." Meanwhile let us return and witness the progress of the battle, on the Rebel left,--where we were looking on, at 10:30 o'clock. Evans had then just posted his eleven companies of Infantry on Buck Ridge, with one of his two guns on his left, near the Sudley road, and the other not far from the Robinson House, upon the Northern spur of the elevated plateau just South of Young's Branch, and nearly midway between the Sudley road and Stone Bridge. The battle, as we have seen, has opened. As Burnside's Brigade appears on the slope, to the North of Buck Ridge (or Hill), it is received by a rapid, well-sustained, and uncomfortable, but not very destructive fire, from Evans's Artillery, and, as the Union regiments press forward, in column, full of impulsive ardor, the Enemy welcomes the head of the column with a hot musketry-fire also, delivered from the crest of the elevation behind which the Rebel Infantry lie flat upon the ground. This defense by Evan's demi-Brigade still continues, although half an hour, or more, has elapsed. Burnside has not yet been able to dislodge the Enemy from the position. Emboldened to temerity by this fact, Major Wheat's Louisiana battalion advances through the woods in front, upon Burnside, but is hurled back by a galling fire, which throws it into disorder and flight.