In early June 1863, General Robert E. Lee led the Confederate Army of Northern Virginia out of its camps in Virginia and north into Pennsylvania, hoping a victory on Northern soil would weaken Northern resolve and possibly bring a negotiated peace and Southern independence, while the Union Army of the Potomac moved to stay between the Confederates and Washington, D.C. On June 25, three brigades of Confederate cavalry under Major General J.E.B. Stuart, about 5,000 men, left Lee's main body on a raid around the Union forces, and by June 29 Stuart's men had reached Union Mills, Maryland, unaware of Lee's location but knowing Union cavalry was near Littlestown, Pennsylvania, about 6 miles to the northwest. To avoid that cavalry, Stuart moved toward Hanover on June 30, not knowing that Brigadier General H. Judson Kilpatrick's 3rd Cavalry Division was also heading there, and the resulting clashes in Hanover became an important prelude to the Battle of Gettysburg. That morning, Stuart's main column approached Hanover on the Westminster Road as Kilpatrick's Union cavalry came from Littlestown along Frederick Street, and by about 10:00 a.m. most of Kilpatrick's force had passed through Hanover, leaving a rear guard of about 40 men from the 18th Pennsylvania Cavalry under 2nd Lieutenant Henry Clay Potter southwest of town. When Potter's men neared a small Confederate detail leading Stuart's column on the Westminster Road, the Confederates rode onto Frederick Street and demanded their surrender, but Potter's detachment charged through in an effort to escape capture and rejoin its regiment closer to Hanover. Soon afterward, the initial Confederate attack followed, with the 13th Virginia and elements of the 9th Virginia Cavalry charging along Frederick Street while the 2nd North Carolina Cavalry converged from side streets and alleys against the Union column.