McDowell, after resting his troops for two days at Centreville, thought the time for an engagement was now at hand, so on Sunday, July 21st, at half-past two in the morning, the men were roused for the coming conflict. Their dream of easy victory had already received a rude shock, for on their second day at Centreville a skirmish between two minor divisions of the opposing armies resulted in the defeat of the Union forces with some loss. Ambrose E. Burnside and William T. Sherman were at this time subordinate officers under General McDowell. Burnside, who figured later in the far more disastrous battle of Fredericksburg, and Sherman, distinguished for his march to the sea. The Union plan was that General Tyler should lead his division westward and cross Bull Run at the Stone Bridge about four miles from Centreville, and the remainder of the army under Hunter and Heintzelman was to make a circuit of several miles through a dense wood and cross Bull Run at Sudley's Ford. The plan was to attack the Confederate left wing. The march to Sudley's Ford was slower than expected and it was almost noon before this division of the army reached the field near Stone Bridge. General Tyler early in the day opened fire at Stone Bridge on the Confederates under General Evans, but merely kept up a desultory fire. As the morning wore away the Confederates suddenly discovered clouds of dust rising above the treetops along the Warrenton turnpike, which told them that the main Federal army was on them. Evans quickly turned about and made ready for battle and waited calmly for the approach of the enemy. Presently there was a glimmer of sunlight reflected from burnished steel among the trees and Colonel Burnside led the Federal army from the woods and without delay the battle began and raged furiously. Meanwhile Generals Beauregard and Johnston were at Manassas, about four miles from the scene of battle, with part of the Confederate army, and had been planning an attack on the Federal left, but on hearing the roar of the cannon and the rattle of the musketry became convinced that the Federals were making their main attack on the Confederate left, and both galloped at full speed to the scene of battle, after leaving orders to the remainder of the army to be brought up to reënforce the small force of Confederates who were trying to hold back the Federals. They arrived on the field at the moment when General Bee's brigade was being driven back. General Bee, in trying to rally his men, called their attention to the fact that Thos. J. Jackson's brigade was standing like a stone wall, and it was here that Jackson won his name of "Stonewall."