In June 1863, as Confederate Gen. J.E.B. Stuart led his cavalry division north across the Potomac River into Maryland and about 400 Federals and civilians were captured and then paroled in Brookeville, Confederate Gen. Fitzhugh Lee’s brigade continued north toward Hood’s Mill. Near Cooksville, Capt. R.E. Duvall’s Co. A, Purnell Legion Md. Cavalry, had bivouacked on the National Road with two ordnance rifles of Capt. W.D. Rank’s Battery H, 3rd Pa. Artillery, which Duvall was escorting to Relay in Baltimore County for the defense of the Thomas Viaduct on the Baltimore and Ohio Railroad. Before dawn on June 29, when Stuart’s advance drove in the Union pickets, Duvall sent Sgt. Andrew Duncan and Pvt. Jonathan Norris back to Frederick to warn Gen. George G. Meade of the Confederate presence, then retreated under cover of darkness, losing some camp equipment and four horses but saving his men and Rank’s guns. Near Poplar Springs he met Col. John B. Mclntosh’s cavalry brigade, which offered protection, and although Gen. Robert Schenck reported Duvall’s company and the two guns captured when they did not reach Relay as expected, he learned their true status two days later.