Robert Knox Sneden, Blockade of the Potomac by Rebels, Winter of 1861 (1865)

This map was created by Robert Knox Sneden, a Union soldier and mapmaker, to depict the Confederate’s blockade of the Potomac during the winter of 1861 and 1862. In 1861, after the Battle of First Manassas, the Confederate Army moved to fortify Northern Virginia in order to prepare for another advance by the Union Army. They focused on controlling and fortifying areas along the Potomac River to limit supply routes to Washington D.C. The capital city was controlled by the Union, but there were only three transportation routes that connected D.C. to the rest of the country. Two of these routes followed the Potomac River. Confederate forces successfully cut off one of the railroads to the city, then moved to fortify along the Potomac River to prevent ships from entering Washington D.C. One of the bluffs they decided to fortify was Cockpit Point, which is depicted on the map. The Confederate’s fortifications worked and naval traffic along the Potomac began to decline. At Cockpit Point, the Union attempted to drive out the Confederates using two gunboats, but were unsuccessful. Eventually, in March of 1862,  the Confederate Army evacuated Northern Virginia. This left the forts to the control of the Union, allowing naval traffic to return to the Potomac to D.C.