Stuart faced a difficult assignment—locate the Union cavalry and prevent it from severing Gen. Lee's avenue of retreat to Williamsport and the Potomac River.

He first encountered Federal resistance at Beaver Creek Bridge, 4.5 miles (7.2 km) north of Boonsboro.

By 11 a.m., the Confederate cavalry had pushed forward to several mud-soaked fields, where fighting on horseback was nearly impossible, forcing Stuart's troopers and Brig.

H. Judson Kilpatrick's and John Buford's Union cavalry divisions to dismount and slug it out like infantry.

By mid-afternoon, the Union left under Kilpatrick crumbled as the Federals ran low on ammunition under increasing Confederate pressure.