“On the morning of the 20th the Federal signal officer on Sugar Loaf Mountain, in Maryland, reported ’the enemy have moved away from Leesburg.’  This Banks wired to McClellan, whereupon the latter wired to Stone, at Poolesville, that a heavy reconnoissance would be sent out that day, in all directions, from Dranesville, concluding:  ’You will keep a good lookout upon Leesburg, to see if this movement has the effect to drive them away.  Perhaps a slight demonstration on your part would have the effect to move them.’  McClellan desired Stone to make demonstrations from his picket line along the Potomac, but did not intend that he should cross the river, in force, for the purpose of fighting.  Late in the day Stone reported that he had made a feint of crossing, and at the same time had started a reconnoissance from Harrison’s Island toward Leesburg, when the enemy’s pickets retired to intrenchments.  That ‘slight demonstration’ brought on the battle of Ball’s Bluff on Monday, October 21st.  On the morning of the 21st, McCall retired from Evan’s front to his camp at Prospect Hill, 4 miles up the river from the Chain bridge.  From his point of observation, at the earthworks called ‘Fort Evans,’ to the eastward of Leesburg, overlooking the fords at Conrad’s and Edwards’ ferries and Ball’s Bluff, Evans, at 6 a.m. on the 21st, found that the enemy of Stone’s division had effected a crossing at Edwards’ Ferry and at Ball’s Bluff, 4 miles above.  He promptly sent four companies from his Mississippi regiments and two companies of cavalry, under the command of Lieutenant-Colonel W.H.  Jenifer to the assistance of Captain Duff, to hold the enemy in check until his plan of attack should be developed.  Colonel Jenifer immediately engaged the Federal advance and drove it back toward Ball’s Bluff.

“The force that had crossed at Harrison’s Island, about midnight of the 20th, was part of the command of Colonel Baker, some 300 men under Col.  Charles Devens, of the Fifteenth Massachusetts.  Its object was to capture a Confederate camp that had been reported to be about a mile from the river.  This force advanced to an open field surrounded by woods, where it halted until it could be joined by a company from the Twentieth Massachusetts, which had been left on the bluff, on the Virginia side, to protect the Federal return.  Devens, at daybreak, pushed forward with a few men to reconnoiter, and, in person, went to within sight of Leesburg.  Thinking he had not been discovered Devens determined to remain and sent back to his brigade commander, Colonel Baker, for reinforcements.  The latter consulted his division commander, General Stone, and obtained permission to either withdraw Devens or to send over reinforcements to him.  He promptly directed Devens to hold his position and said that he would support him in person with the rest of his brigade.  The boats and flats that had been provided for crossing the Potomac from the Maryland shore to Harrison’s Island and from the latter to the Virginia shore were entirely inadequate, and it was nearly noon before Devens’ regiment of 625 men was closed up on the Virginia shore.