In April 1861, President Abraham Lincoln ordered a naval blockade of the major southern ports from Virginia to Texas to weaken the Confederate war effort by stopping cotton exports to European buyers and preventing war materials and manufactured goods from entering southern ports. Wilmington became a center of blockade running because the region's two navigable inlets, separated by Cape Fear and Frying Pan Shoals, made effective blockading extremely difficult, while Confederate defenses at Fort Caswell and Fort Fisher guarded the approaches. By the end of the Civil War, Fort Fisher, with 46 large guns and a sea-face nearly a mile long, was the largest fortification in the South. New Inlet was the preferred channel for blockade runners on the Cape Fear River, and ships, primarily British-built steamers, came by night from Bermuda and the Bahamas carrying war materials, manufactured goods, and luxury items, then returned with cotton for British textile mills. More than 500 successful runs through Wilmington's blockade were estimated, but the trade remained dangerous: across the South, 136 blockade runners were captured and 85 destroyed, and near New Inlet at least 13 British, Confederate, and Union vessels were lost during the Civil War.