The Union Blockade is the name given the naval actions between 1861 and 1865, during the American Civil War, wherein the Union navy set out to cut the supply of trade goods, supplies and arms to and from the Confederacy. Ships that tried to evade the blockade were called blockade-runners. They were mostly newly built ships that were fast but had small capacity for cargo. They were operated by the British, and ran between Confederate controlled ports and the neutral ports of Havana, Nassau, and Bermuda, where British suppliers had set up supply bases.
President Abraham Lincoln declared the blockade on April 19, 1861. His strategy, part of an overall plan of General Winfield Scott, required 3,500 miles of Confederate coastline and 12 major ports including New Orleans, Mobile, Richmond, Virginia, Charleston, Savannah, and Wilmington, NC. The Union commissioned 500 ships to get this done. They destroyed or captured about 1,500 blockade-runners during the war. Five out of six blockade-runners were successful, however. Yet the blockade-runners only carried a fraction of the usual cargo, so Confederate cotton exports were reduced 95 percent compared to prewar levels.
The Union Blockade eventually ruined the Southern economy and cost very few lives. It severely reduced cotton exports and choked off munitions imports. The measure of the blockade’s effectiveness was not how many ships made it through, but how many never tried it and the overall reduction of imports and exports. The interdiction of coastal traffic meant the only way to get around was on the south’s rickety railroad system. The blockade caused other problems as well. For example, it made food distribution difficult. The south was producing enough food during the war, but often could not get it to eh civilians and soldiers who needed it.