Throughout the American Civil War, blockade runners were seagoing steam ships that were used to get through the Union blockade that extended some along the Atlantic and Gulf of Mexico coastlines and the lower Mississippi River. The Confederate states were largely without industrial capability and could not provide the quantity of arms and other supplies needed to fight against the industrial North. To meet this need blockade runners were built in Scotland and England and were used to import the guns, ordnance and other supplies that the Confederacy desperately needed, in exchange for cotton that the British textile industry needed greatly. To penetrate the blockade, these relatively lightweight shallow draft ships, mostly built in British shipyards and specially designed for speed, but not suited for transporting large quantities of cotton, had to cruise undetected, usually at night, through the Union blockade. The typical blockade runners were privately owned vessels often operating with a letter of marque issued by the Confederate States of America. If spotted, the blockade runners would attempt to outmaneuver or simply outrun any Union ships on blockade patrol, often successfully.
To avert wartime legalities and confiscation, these vessels would carry cargoes to and from neutral ports, often located in Nassau and Cuba. Neutral merchant ships in turn carried these cargoes, usually coming from or destined to Great Britain or other points abroad. Outbound ships chiefly exported cotton, tobacco and other goods for trade and revenue, while also carrying important mail and correspondence to suppliers and other interested parties in Europe, most often in England. Inbound ships usually brought badly needed supplies and mail to the Confederacy. Most of the guns and other ordnance of the Confederacy were imported from Britain via these blockade runners. Some runners made many successful runs, while many others were either captured or destroyed.
Historian John E. Clark called the British blockade running "the aquatic equivalent of the Ho Chi Minh Trail." Historians estimated that 2,500–2,800 attempts were made to run the blockade, with at least an 80% success rate. As a result, the blockade runners operating from Britain escalated the war by two years and killed 400,000 additional soldiers and civilians on both sides. By the end of the Civil War, the Union Navy had captured more than 1,100 blockade runners and had destroyed or run aground another 355 vessels. But more importantly, it had reduced the South's exports of cotton by 95% from pre-war levels, devaluing its currency and severely damaging its economy.
Background
When the American Civil War broke out on April 12, 1861, the newly formed Confederate States of America had no ships to speak of in its navy. In the months leading up to the war, the Confederate government sought the help of Great Britain to overcome this, as much of Britain's industry depended on cotton exports from the plantations of the South. Although officially neutral, the British became the primary shipbuilders and source of military and other supplies for the Confederate government for the duration of the American Civil War.
In 1861 the Confederate naval fleet consisted of only about 35 ships, of which 21 were steam-driven. The Confederacy was in dire need of many basic supplies. Without the resources of the industrial North, it had to look elsewhere for its supplies. Coming to their aid, Raphael Semmes, an experienced former U.S. naval captain, devised a plan by which to thwart the naval supremacy of the North. He proposed a militia of privateers that would both strike at the North's merchant ships and provide supplies to the South by outrunning or evading the ships of the Union blockade. Confederate President Jefferson Davis approved of the plan.
On April 15 President Lincoln issued his first proclamation, calling out 75,000 troops in response to the Confederate bombardment of Fort Sumter. On April 17 Davis issued a proclamation, offering a letter of marque to anyone who would offer their ship in the service of the Confederacy. To this end British investors were the most prolific in offering such aid.