<P> One historically notable naval action was the attack of the Confederate submarine H.L. Hunley, a hand - powered submarine launched from Charleston, South Carolina, against Union blockade ships . On the night of 17 February 1864, Hunley attacked Housatonic . The Housatonic sank with the loss of five crew; the Hunley also sank, taking her crew of eight to the bottom . </P> <P> The first victory for the U.S. Navy during the early phases of the blockade occurred on 24 April 1861, when the sloop Cumberland and a small flotilla of support ships began seizing Confederate ships and privateers in the vicinity of Fort Monroe off the Virginia coastline . Within the next two weeks, Flag Officer Garrett J. Pendergrast had captured 16 enemy vessels, serving early notice to the Confederate War Department that the blockade would be effective if extended . </P> <P> Early battles in support of the blockade included the Blockade of the Chesapeake Bay, from May to June 1861, and the Blockade of the Carolina Coast, August--December 1861 . Both enabled the Union Navy to gradually extend its blockade southward along the Atlantic seaboard . </P> <P> In early March 1862, the blockade of the James River in Virginia was gravely threatened by the first ironclad, CSS Virginia in the dramatic Battle of Hampton Roads . Only the timely entry of the new Union ironclad Monitor forestalled the threat . Two months later, Virginia and other ships of the James River Squadron were scuttled in response to the Union Army and Navy advances . </P>

Battle that lead to the union's control of the mississippi river