The blockade runners of the American Civil War were seagoing steam ships that were used to make their way through the Union blockade that extended some 3,500 miles (5,600 km) along the Atlantic and Gulf of Mexico coastlines and the lower Mississippi River. Blockade runners imported from England most of the guns and other ordinance the Confederacy needed. To get through the blockade these ships, many of them built in British ship yards, specially designed for speed, had to cruise by undetected, usually at night. 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 runners would attempt to outmaneuver or simply outrun any Union ships on blockade patrol.