A blockade runner is usually a lighter-weight ship used for evading a naval blockade of a port or strait, as opposed to confronting the blockaders to break the blockade. Very often blockade running is done in order to transport cargo, for example to bring food or arms to a blockaded city. In other cases the blockade runners would carry mail in an attempt to communicate with the outside world.
Blockade runners are often the fastest ships available, and come lightly armed and armored. Their operations are quite risky since blockading fleets would not hesitate to fire on them. However, the potential profits (economically or militarily) from a successful blockade run are tremendous, so blockade-runners typically had excellent crews. Although having modus operandi similar to that of smugglers, blockade-runners are often operated by state's navies as part of the regular fleet. Notable users of blockade runners include the Confederate States of America during the American Civil War and Germany during the World Wars.
There were numerous blockades and attempts at blockade running during the Peloponnesian War.
During the Punic Wars, the Carthaginian Empire attempted to get around Roman blockades of its ports and strongholds. At one point, blockade runners brought in the only food reaching the city of Carthage,
During the American Civil War, blockade running became a major enterprise for the Confederacy due to the Union's Anaconda Plan, which sought to cut off all the Confederacy's overseas trade. Twelve major ports and approximately 3,500 miles of coastline along the Confederate States were patrolled by some 500 ships that were commissioned by the Union government. Great Britain played a major role on the blockade running business, as they had huge investments in the south and were the recipients of many commodities exported goods, especially cotton. Great Britain also had control over many of the neutral ports in the Caribbean, as well as Atlantic ports off the East Coast of the United States, such as the Bahamas and Bermuda. To protect their interests British investors had engineered steamships that were longer, narrower and considerably faster than most of the conventional steamers guarding the American coastline, thus enabling them to outmaneuver and outrun Union ships on blockade patrol. Among the more notable of these premier vessels was the CSS Advance that completed more than 20 successful runs through the Union blockade before being captured. These vessels also served to import badly needed supplies, especially firearms, and also served to bring mail to and from the Confederacy. The blockade played a major role in the Union's victory over the Confederate states. 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.