Longstreet assembled his staff and trained his brigade incessantly. On July 16, Union Brigadier General Irvin McDowell began marching his army toward Manassas Junction. Longstreet's brigade first saw action at Blackburn's Ford on July 18, when it collided with McDowell's advance division under Brigadier General Daniel Tyler, clashing heavily with the brigade of Israel B. Richardson. An infantry charge pushed Longstreet's men back, and in his own words Longstreet "rode with sabre in hand for the leading files, determined to give them all that was in the sword and my horse's heels, or stop the break". Colonel Jubal Early's brigade arrived to reinforce Longstreet. One of Early's regiments, the 7th Virginia, fired a volley while Longstreet was still in front of its position, forcing him to dive off of his horse and onto the ground. Under the renewed Confederate strength, the Union left wavered. Tyler withdrew, as he had orders not to bring on a general engagement. The battle preceded the First Battle of Bull Run (First Manassas). When the main attack came at the opposite end of the line on July 21, Longstreet's brigade endured artillery fire for nine hours but played a minor role in the fighting. Between 5 and 6 in the evening, Longstreet received an order from Brigadier General Joseph E. Johnston instructing him to take part in pursuit of the Federal troops, who had been defeated and were fleeing the battlefield. He obeyed, but when he met the brigade of Brigadier General Milledge Bonham, Bonham, who outranked Longstreet, ordered him to retreat. An order soon arrived from Johnston ordering the same. Longstreet was infuriated that his commanders would not allow a vigorous pursuit of the defeated Union Army. His Chief of Staff, Moxley Sorrel, recorded that he was "in a fine rage. He dashed his hat furiously to the ground, stamped, and bitter words escaped him." He quoted Longstreet as saying afterwards, "Retreat! Hell, the Federal army has broken to pieces."