Readily brushing aside the remaining small Federal garrisons in a series of minor engagements, Early (with Breckinridge's men now a part of the Army of the Valley) proceeded northward and then east from the valley across the South Mountain range. Near Frederick, Maryland, the force was delayed by a full day at the Battle of Monocacy by Lew Wallace. On July 11, Early threatened Washington before withdrawing two days later. On July 24, after returning to the Shenandoah, the Army of the Valley won its last major battle, Second Kernstown, defeating George Crook's VIII Corps. Early dispatched much of his cavalry under John McCausland to raid and subsequently burn much of Chambersburg, Pennsylvania (in apparent retaliation for Hunter's burning of the Virginia Military Institute).