...tary affairs that still held north of the Potomac the great army—on its rolls, March 1, 1862, 222,000 men—that McClellan had, during more than half a year, been collecting and organizing, President Lincoln ordered that an advance of the whole army of the Potomac, except such a force as was necessary to defend Washington, should be made, on or before the 22d of February, to drive back the opposing Confe...