The Battle of Ball's Bluff was the result of a mistake. The previous evening, Capt. Chase Philbrick, Co. H, 15th Massachusetts, led a small reconnaissance patrol across the river to determine the results of some earlier Confederate troop movements. Philbrick soon spotted what he thought was an enemy camp and reported this news. The "camp," in fact was a row of trees mistaken for tents.
On orders from Brig. Gen. Charles P. Stone, Col. Charles Devens' crossed a 300-man force to raid this "camp" but soon discovered the mistake. Devens remained where he was and sent word to General Stone. His decision to stay led to the battle. On hearing of the mistake about the camp, Stone sent Devens the remainder of his regiment with orders to reconnoiter closer to Leesburg. He also ordered Col. Edward D. Baker, a U.S. Senator and friend of President Lincoln, to take command of the force, evaluate the situation and use his own discretion about whether to advance more men across the river or to retire those already there.
Unknown to either Stone or Baker, Devens' original raiding party had already engaged pickets of the 17th Mississippi while waiting to hear from General Stone. The fighting thus began without Stone's knowledge. From there, both sides gradually reinforce during the day. Thus, a small reconnaissance became a battle.