During the Battle of Chancellorsville, Stoneman's Corps, including Gregg's Division, was sent on a nine-day raid around Lee's left flank to destroy facilities in the rear of the Army of Northern Virginia. Although the raid caused much destruction, it achieved little strategically, and Stoneman was widely criticized for lack of aggression and for failing to draw Confederate forces away from the main battle. Maj. Gen. Alfred Pleasonton then replaced Stoneman in command of the Cavalry Corps. At the start of the Gettysburg Campaign, Lee's stealthy movement away from the Fredericksburg area caused Union concern, and Pleasonton was ordered to discover where the Confederate army was going. A surprise attack on Maj. Gen. J.E.B. Stuart at Brandy Station produced the largest predominantly cavalry engagement of the war. The opening assault crossed the Rappahannock River at Beverly Ford under Brig. Gen. John Buford, while Gregg led the 2nd and 3rd Divisions across Kelly's Ford to strike the Confederate flank and rear on Fleetwood Hill, where Stuart's headquarters stood. Fierce saber and hand-to-hand fighting followed, and the Confederates repulsed Gregg. The battle ended essentially as a draw, but it surprised and humiliated Stuart, and orders left behind gave valuable intelligence about Lee's plans to invade Maryland and Pennsylvania.