The echoes of Major Anderson's 100-gun salute as he lowered the flag at Fort Sumter had scarcely died away before the USS Sabine began the blockade of Pensacola, Florida. Within six days, April 19, 1861, President Lincoln officially declared a blockade of the seceded states, and eight days later added the newest members of the Confederacy, Virginia and North Carolina.
"Paper blockade" though it was at first, requiring a sadly insufficient Navy to patrol a more than 3,500-mile coastline from Cape Henry, Virginia to Texas and the Mexican border, it was a necessary move to assert ascendancy over the almost navy-less South, and to warn European powers to keep hands off. Foreign nations at the start derided the blockade, although officially they respected it, but daring individuals saw it as an opportunity for quick and enormous profits, and the "big business" of blockade running began, mostly from Nassau and Bermuda.
Commodore Silas Stringham had overall command in the early months of the blockade, but it soon became necessary to reorganize the blockading forces into two groups, the North and South Blockading Squadrons. Commodore Louis M. Goldsborough took over the North Squadron and the later Rear Admiral Samuel F. Du Point was given the South Squadron.
Many blockade runners were specially built for their mission. Long and narrow, low in the water, paddle- or screw-propelled, burning anthracite coal and venting the gases from retractable smokestacks, these gray-painted, shallow-draft vessels could glide almost unseen at night between the blockading ships into the shoal coastal waters where the big ships dared not follow. It was dangerous work, since the unarmed runners could not fight back, but the gains were astronomical. One successful voyage could pay for the ship, so that succeeding runs meant almost clear profit. The most lucrative cargoes --hence the most numerous--were civilian goods and luxuries; in desperation the Confederate Government fitted out its own blockade runners to bring in war essentials: rifles, lead, powder, shoes, medical supplies,, and the like.
One by one, as the Union Navy grew in size and efficiency, Southern ports were sealed off. The last was Wilmington, North Carolina; with the capture of its guardian fort, Fort Fisher, on January 15, 1865, "the last gateway between the Confederate States and the outside world" was closed.