On July 21, 1861, John participated in the First Battle of Bull Run, a disastrous Union defeat just a few miles from the national capital. Most of the Union Army panicked and fled in a disorderly retreat. For a time during the tumultuous battle, Meigs directed the fire and movement of troops in the absence of commanding officers. Meigs' unit fell back on Fairfax, Virginia. Without orders to do so, John left the unit and returned to the capital. He reached his parents' home at about 8 A.M., and let them know he was uninjured. He said he left Company M to report to Lieutenant General Winfield Scott, commander-in-chief of all Union armed forces. Although John wished to return to his unit, his father ordered him to depart for West Point after reporting to General Scott.