After Confederate Gen. Robert E. Lee's victory over Union Gen. John Pope at the Second Battle of Manassas, Lee invaded Maryland to reap the fall harvest, gain recruits, win foreign recognition of the Confederacy, and perhaps compel the Union to sue for peace. The Army of Northern Virginia crossed the Potomac River on September 4, 1862, and Lee divided his force, sending Gen. Thomas J. "Stonewall" Jackson's corps to capture Harpers Ferry. On September 17 at Antietam Creek, Gen. George B. McClellan's Army of the Potomac fought Lee's men to a bloody draw, and Lee retreated to Virginia on September 18-19. During the campaign, the Army of Northern Virginia marched through Frederick on September 10, 1862, while local Unionists, mostly women, taunted the troops by waving the Stars and Stripes. A year later, John Greenleaf Whittier immortalized one of these women in "The Ballad of Barbara Fritchie," but contrary to the poem, Jackson's command took another street through town. Barbara Fritchie, then aged 96, did wave a flag from her porch when Federal forces marched by, and Whittier may have conflated her with Mrs. Mary Quantrell, who shook a United States flag at Confederates and was ignored. When Whittier's poem was published, it raised patriotic spirits throughout the Union.