 Northern fears of a continued offensive by Robert E. Lee were realized when he launched his Maryland Campaign on September 4, hoping to arouse pro-Southern sympathy in the slave state of Maryland. McClellan's pursuit began on September 5. He marched toward Maryland with six of his reorganized corps, about 84,000 men, while leaving two corps behind to defend Washington. McClellan's reception in Frederick, Maryland, as he marched towards Lee's army, was described by the correspondent for Harper's Magazine:
