"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.