William Swinton, Campaigns of the Army of the Potomac

In the dark hour when the shattered battalions that survived Pope's campaign returned to Washington, General Mc-Clellan, at the request of the President, resumed command of the Army of the Potomac, with the addition thereto of Burnside's command and the corps composing the late Army of Virginia. Whatever may have been the estimate of McClellan's military capacity at this time held by the President, or General Halleck, or Mr. Secretary Stanton, or the Committee on the Conduct of the War, there appears to have been no one to gainsay the propriety of the appointment or dispute the magic of his name with the soldiers he had led. McClellan's reappearance at the head of affairs had the most beneficial effect on the army, whose morale immediately underwent an astonishing change. The heterogeneous mass made up of the aggregation of the remnants of the two armies, and the garrison of Washington, was reorganized into a compact body—a work that had mostly to be done while the army was on the march;¹ and as soon as it became known that Lee had crossed the Potomac, McClellan moved towards Frederick to meet him. The advance was made by five parallel roads, and the columns were so disposed as to cover both Washington and Baltimore; for the left flank rested on the Potomac, and the right on the Baltimore and Ohio Railroad. The right wing consisted of the First and Ninth corps, under General Burnside; the centre, of the Second and Twelfth corps, under General Sumner; and the left wing, of the Sixth Corps, under General Franklin.²