On the 3d of July the enemy approached Martinsburg.
General Sigel, who was in command of our forces there, retreated across the Potomac at Shepherdtown; and General Weber, commanding at Harper's Ferry, crossed the occupied Hagerstown, moving a strong column towards Frederick City.

General Wallace, with Rickett's division and his own command, the latter mostly new and undisciplined troops, pushed out from Baltimore with great promptness, and met the enemy in force on the Monocacy, near the crossing of the railroad bridge.

His force was not sufficient to insure success, but he fought the enemy nevertheless, and although it resulted in a defeat to our arms, yet it detained the enemy, and thereby served to enable General Wright to reach Washington with two division of the 6th corps, and the advance of the 19th corps, before him.

From Monocacy the enemy moved on Washington, his cavalry advance reaching Rockville on the evening of the 10th.

On the 12th a reconnoissance was thrown out in front of Fort Stevens, to ascertain the enemy's position and force.