On June 10, 1863, Mosby led 100 men on a raid across the Potomac River to attack the Union camp at Seneca, Maryland. After routing a company of the Sixth Michigan Cavalry and burning their camp, Mosby reported the success to J.E.B. Stuart. This drew Stuart's attention to Rowser's Ford. Mosby had crossed the Potomac there, and during the night of June 27 Stuart's forces would use the same crossing while separated from Lee's army, and thus didn't arrive at Gettysburg until the afternoon of the second day of the battle. Thus, some analysts claim Lee stumbled into the battle without his cavalry, partly because of Mosby's successful skirmish at Seneca three weeks earlier.