On June 24, 1863, Gen. J.E.B. Stuart left 3,000 cavalrymen in Rectortown, Virginia, to monitor Federal activity and led three Confederate cavalry brigades to Haymarket. After encountering Union Gen. Winfield S. Hancock’s corps marching north, Stuart sent Gen. Robert E. Lee a dispatch, never received, predicting where Hancock would cross the Potomac River. Stuart’s cavalry rode through Fairfax Court House and reached Dranesville on June 27. That night, 5,000 Confederate cavalrymen crossed into Maryland at Rowser’s Ford, passing between the Union army and Washington. The rain-swollen river made crossing difficult for artillery and ambulances, but by 3 a.m. on Sunday, June 28, they had crossed without alerting residents. Stuart then seized the Chesapeake and Ohio Canal between Locks 23 and 24 in hopes of disrupting commerce and an important Federal supply line. Cavalrymen turned a barge lengthwise into an improvised bridge, captured at least a dozen boats carrying Union soldiers and grain, burned nine of them, damaged the wooden gates at Lock 23 and Guard Lock 2, and drained that section of the canal by breaching the towpath embankment. The canal did not become operational again until June 30. After resting, Stuart’s forces split into two columns to converge that afternoon at Rockville, the Montgomery County seat. Gen. Wade Hampton’s brigade moved up Seneca Road to Darnestown, while Stuart, with the other two brigades under Gens. Fitzhugh Lee and W.H.F. Lee, the latter led by Col. John R. Chambliss, rode south toward Offutts Crossroads, present-day Potomac, and onto Great Falls Road.