Union blockade The Union blockade in the American Civil War was a naval tactic by the Northern government to prevent the Confederacy from trading . The blockade was proclaimed by President Abraham Lincoln in April 1861 , and required the closure of of Atlantic and Gulf coastline , including 12 major ports , notably New Orleans and Mobile , Alabama . Many attempts to run the blockade were successful , but those ships fast enough to evade the U . S . Navy could only carry a small fraction of the supplies needed . These blockade runner s were operated largely by the British , making use of neutral ports such as Havana , Cuba , Nassau , Bahamas and Bermuda . The U . S . commissioned 500 ships , which destroyed or captured about 1 , 500 blockade runners over the course of the war . Proclamation of blockade and legal implications . On 19 April 1861 , President Lincoln issued a " Proclamation of Blockade Against Southern Ports " : Whereas an insurrection against the Government of the United States has broken out in the States of South Carolina , Georgia , Alabama , Florida , Mississippi , Louisiana , and Texas , and the laws of the United States for the collection of the revenue cannot be effectually executed therein comformably to that provision of the Constitution which requires duties to be uniform throughout the United States : And whereas a combination of persons engaged in such insurrection , have threatened to grant pretended letters of marque to authorize the bearers thereof to commit assaults on the lives , vessels , and property of good citizens of the country lawfully engaged in commerce on the high seas , and in waters of the United States : And whereas an Executive Proclamation has been already issued , requiring the persons engaged in these disorderly proceedings to desist therefrom , calling out a militia force for the purpose of repressing the same , and convening Congress in extraordinary session , to deliberate and determine thereon : Now , therefore , I , Abraham Lincoln , President of the United States , with a view to the same purposes before mentioned , and to the protection of the public peace , and the lives and property of quiet and orderly citizens pursuing their lawful occupations , until Congress shall have assembled and deliberated on the said unlawful proceedings , or until the same shall ceased , have further deemed it advisable to set on foot a blockade of the ports within the States aforesaid , in pursuance of the laws of the United States , and of the law of Nations , in such case provided . For this purpose a competent force will be posted so as to prevent entrance and exit of vessels from the ports aforesaid . If , therefore , with a view to violate such blockade , a vessel shall approach , or shall attempt to leave either of the said ports , she will be duly warned by the Commander of one of the blockading vessels , who will endorse on her register the fact and date of such warning , and if the same vessel shall again attempt to enter or leave the blockaded port , she will be captured and sent to the nearest convenient port , for such proceedings against her and her cargo as prize , as may be deemed advisable . And I hereby proclaim and declare that if any person , under the pretended authority of the said States , or under any other pretense , shall molest a vessel of the United States , or the persons or cargo on board of her , such person will be held amenable to the laws of the United States for the prevention and punishment of piracy . In witness whereof , I have hereunto set my hand , and caused the seal of the United States to be affixed . Done at the City of Washington , this nineteenth day of April , in the year of our Lord one thousand eight hundred and sixty - one , and of the Independence of the United States the eighty - fifth . Recognition of the Confederacy . In his " Memoirs of Service Afloat , " Raphael Semmes contended that the announcement of a blockade carried de facto recognition of the Confederate States of America as an independent national entity since countries do not blockade their own ports but rather " close " them . Under international law and maritime law , however , nations had the right to stop and search neutral ships in international waters if they were suspected of violating a blockade , something port closures would not allow . In an effort to avoid conflict between the United States and Britain over the searching of British merchant vessels thought to be trading with the Confederacy , the Union needed the privileges of international law that came with the declaration of a blockade . However , by effectively declaring the Confederate States of America to be belligerent s — rather than insurrection ists , who under international law would not be legally eligible for recognition by foreign powers — Lincoln opened the way for European powers such as Britain and France to recognize the Confederacy . Britain ' s proclamation of neutrality was consistent with the position of the Lincoln Administration under international law — the Confederates were belligerents — giving them the right to obtain loans and buy arms from neutral powers , and giving the British the formal right to discuss openly which side , if any , to support . Operations . Scope . A joint Union military - navy commission , known as the Blockade Strategy Board , was formed to develop plans for seizing key Southern ports to utilize as Union bases of operations to expand the blockade . It first met in June 1861 in Washington , D . C . , under the leadership of Captain Samuel F . Du Pont . In the initial phase of the blockade , Union forces concentrated on the Atlantic Coast . The November 1861 capture of Port Royal in South Carolina provided the Federals with an open ocean port and repair and maintenance facilities in good operating condition . It became an early base of operations for further expansion of the blockade along the Atlantic coastline , including the Stone Fleet . Apalachicola , Florida , received Confederate goods traveling down the Chattahoochee River from Columbus , Georgia , and was an early target of Union blockade efforts on Florida ' s Gulf Coast . Another early prize was Ship Island , which gave the Navy a base from which to patrol the entrances to both the Mississippi River and Mobile Bay . The Navy gradually extended its reach throughout the Gulf of Mexico to the Texas coastline , including Galveston and Sabine Pass . With 3 , 500 miles ( 5 , 600 km ) of Confederate coastline and 180 possible ports of entry to patrol , the blockade would be the largest such effort ever attempted . The United States Navy had 42 ships in active service , and another 48 laid up and listed as available as soon as crews could be assembled and trained . Half were sailing ships , some were technologically outdated , most were at the time patrolling distant oceans , one served on Lake Erie and could not be moved into the ocean , and another had gone missing off Hawaii . At the time of the declaration of the blockade , the Union only had three ships suitable for blockade duty . The Navy Department , under the leadership of Navy Secretary Gideon Welles , quickly moved to expand the fleet . U . S . warships patrolling abroad were recalled , a massive shipbuilding program was launched , civilian merchant and passenger ships were purchased for naval service , and captured blockade runners were commissioned into the navy . In 1861 , nearly 80 steamers and 60 sailing ships were added to the fleet , and the number of blockading vessels rose to 160 . Some 52 more warships were under construction by the end of the year . By November 1862 , there were 282 steamers and 102 sailing ships . By the end of the war , the Union Navy had grown to a size of 671 ships , making it the largest navy in the world . By the end of 1861 , the Navy had grown to 24 , 000 officers and enlisted men , over 15 , 000 more than in antebellum service . Four squadrons of ships were deployed , two in the Atlantic and two in the Gulf of Mexico . Blockade service . Blockade service was attractive to Federal seamen and landsmen alike . Blockade station service was considered the most boring job in the war but also the most attractive in terms of potential financial gain . The task was for the fleet to sail back and forth to intercept any blockade runners . More than 50 , 000 men volunteered for the boring duty , because food and living conditions on ship were much better than the infantry offered , the work was safer , and especially because of the real ( albeit small ) chance for big money . Captured ships and their cargoes were sold at auction and the proceeds split among the sailors . When seized the hapless blockade runner " Hope " off Wilmington , North Carolina , in late 1864 , the captain won $ 13 , 000 ( $ today ) , the chief engineer $ 6 , 700 , the seamen more than $ 1 , 000 each , and the cabin boy $ 533 , compared to infantry pay of $ 13 ( $ today ) per month . The amount garnered for blockade runners widely varied . While the little " Alligator " sold for only $ 50 , bagging the " Memphis " brought in $ 510 , 000 ( $ today ) ( about what 40 civilian workers could earn in a lifetime of work ) . In four years , $ 25 million in prize money was awarded . Blockade runners . While a large proportion of blockade runner s did manage to evade the Union ships , as the blockade matured , the type of ship most likely to find success in evading the naval cordon was a small , light ship with a short draft — qualities that facilitated blockade running but were poorly suited to carrying large amounts of heavy weaponry , metals , and other supplies badly needed by the South . To be successful in helping the Confederacy , a blockade runner had to make many trips ; eventually , most were captured or sunk . Nonetheless , five out of six attempts to evade the Union blockade were successful . During the war , some 1 , 500 blockade runners were captured or destroyed . Ordinary freighters were too slow and visible to escape the Navy . The blockade runners therefore relied mainly on new steamships built in Britain with low profiles , shallow draft , and high speed . Their paddle - wheels , driven by steam engines that burned smokeless anthracite coal , could make . Because the South lacked sufficient sailors , skippers and shipbuilding capability , the runners were built , commanded and manned by British officers and sailors . Private British investors spent perhaps £50 million on the runners ( $ 250 million in U . S . dollars , equivalent to about $ 2 . 5 billion in 2006 dollars ) . The pay was high : a Royal Navy officer on leave might earn several thousand dollars ( in gold ) in salary and bonus per round trip , with ordinary seamen earning several hundred dollars . The blockade runners were based in the British islands of Bermuda and the Bahamas , or Havana , in Spanish Cuba . The goods they carried were brought to these places by ordinary cargo ships , and loaded onto the runners . The runners then ran the gauntlet between their bases and Confederate ports , some apart . On each trip , a runner carried several hundred tons of compact , high - value cargo such as cotton , turpentine or tobacco outbound , and rifles , medicine , brandy , lingerie and coffee inbound . Often they also carried mail . They charged from $ 300 to $ 1 , 000 per ton of cargo brought in ; two round trips a month would generate perhaps $ 250 , 000 in revenue ( and $ 80 , 000 in wages and expenses ) . Blockade runners preferred to run past the Union Navy at night , either on moonless nights , before the moon rose , or after it set . As they approached the coastline , the ships showed no lights , and sailors were prohibited from smoking . Likewise , Union warships covered all their lights , except perhaps a faint light on the commander ' s ship . If a Union warship discovered a blockade runner , it fired signal rockets in the direction of its course to alert other ships . The runners adapted to such tactics by firing their own rockets in different directions to confuse Union warships . In November 1864 , a wholesaler in Wilmington asked his agent in the Bahamas to stop sending so much chloroform and instead send " essence of cognac " because that perfume would sell " quite high " . Confederate patriots held rich blockade runners in contempt for profiteering on luxuries while the soldiers were in rags . On the other hand , their bravery and initiative were necessary for the nation ' s survival , and many women in the back country flaunted imported $ 10 gewgaws and $ 50 hats as patriotic proof that the " damn yankee s " had failed to isolate them from the outer world . The government in Richmond , Virginia , eventually regulated the traffic , requiring half the imports to be munitions ; it even purchased and operated some runners on its own account and made sure they loaded vital war goods . By 1864 , Lee ' s soldiers were eating imported meat . Blockade running was reasonably safe for both sides . It was not illegal under international law ; captured foreign sailors were released , while Confederates went to prison camps . The ships were unarmed ( the weight of cannon would slow them down ) , so they posed no danger to the Navy warships . One example of the lucrative ( and short - lived ) nature of the blockade running trade was the ship " Banshee " , which operated out of Nassau and Bermuda . She was captured on her seventh run into Wilmington , North Carolina , and confiscated by the U . S . Navy for use as a blockading ship . However , at the time of her capture , she had turned a 700 % profit for her English owners , who quickly commissioned and built " Banshee No . 2 " , which soon joined the firm ' s fleet of blockade runners . In May 1865 , CSS " Lark " became the last Confederate ship to slip out of a Southern port and successfully evade the Union blockade when she left Galveston , Texas , for Havana . Impact on the Confederacy . The Union blockade was a powerful weapon that eventually ruined the Southern economy , at the cost of very few lives . The measure of the blockade ' s success was not the few ships that slipped through , but the thousands that never tried it . Ordinary freighters had no reasonable hope of evading the blockade and stopped calling at Southern ports . The interdiction of coastal traffic meant that long - distance travel depended on the rickety railroad system , which never overcame the devastating impact of the blockade . Throughout the war , the South produced enough food for civilians and soldiers , but it had growing difficulty in moving surpluses to areas of scarcity and famine . Lee ' s army , at the end of the supply line , nearly always was short of supplies as the war progressed into its final two years . When the blockade began in 1861 , it was only partially effective . It has been estimated that only one in ten ships trying to evade the blockade were intercepted . However , the Union Navy gradually increased in size throughout the war , and was able to drastically reduce shipments into Confederate ports . By 1864 , one in every three ships attempting to run the blockade were being intercepted . In the final two years of the war , the only ships with a reasonable chance of evading the blockade were blockade runners specifically designed for speed . The blockade almost totally choked off Southern cotton exports , which the Confederacy depended on for hard currency . Cotton exports fell 95 % , from 10 million bales in the three years prior to the war to just 500 , 000 bales during the blockade period . The blockade also largely reduced imports of food , medicine , war materials , manufactured goods , and luxury items , resulting in severe shortages and inflation . Shortages of bread led to occasional bread riots in Richmond and other cities , showing that patriotism was not sufficient to satisfy the demands of housewives . Land routes remained open for cattle drovers , but after the Union seized control of the Mississippi River in summer 1863 , it became impossible to ship horses , cattle and swine from Texas and Arkansas to the eastern Confederacy . The blockade was a triumph of the U . S . Navy and a major factor in winning the war . Confederate response . The Confederacy constructed torpedo boat s , tending to be small , fast steam launches equipped with spar torpedo es , to attack the blockading fleet . Some torpedo boats were refitted steam launches ; others , such as the CSS " David " class , were purpose - built . The torpedo boats tried to attack under cover of night by ramming the spar torpedo into the hull of the blockading ship , then backing off and detonating the explosive . The torpedo boats were not very effective and were easily countered by simple measures such as hanging chains over the sides of ships to foul the screws of the torpedo boats , or encircling the ships with wooden booms to trap the torpedoes at a distance . One historically notable naval action was the attack of the CSS " H . L . Hunley " , a hand - powered submarine launched from Charleston , South Carolina , against Union blockade ships . On the night of 17 February 1864 , " Hunley " attacked . The " Housatonic " sank with the loss of five crew ; the " Hunley " also sank , taking her crew of eight to the bottom . Major engagements . The first victory for the U . S . Navy during the early phases of the blockade occurred on 24 April 1861 , when the sloop " Cumberland " and a small flotilla of support ships began seizing Confederate ships and privateers in the vicinity of Fort Monroe off the Virginia coastline . Within the next two weeks , Flag Officer Garrett J . Pendergrast had captured 16 enemy vessels , serving early notice to the Confederate War Department that the blockade would be effective if extended . Early battles in support of the blockade included the Blockade of the Chesapeake Bay , from May to June 1861 , and the Blockade of the Carolina Coast , August – December 1861 . Both enabled the Union Navy to gradually extend its blockade southward along the Atlantic seaboard . In early March 1862 , the blockade of the James River in Virginia was gravely threatened by the first ironclad , CSS " Virginia " in the dramatic Battle of Hampton Roads . Only the timely entry of the new Union ironclad forestalled the threat . Two months later , " Virginia " and other ships of the James River Squadron were scuttled in response to the Union Army and Navy advances . The port of Savannah , Georgia was effectively sealed by the reduction and surrender of Fort Pulaski on 11 April . The largest Confederate port , New Orleans , Louisiana , was ill - suited to blockade running since the channels could be sealed by the U . S . Navy . From 16 – 22 April , the major forts below the city , Forts Jackson and St . Philip were bombarded by David Dixon Porter ' s mortar schooners . On 22 April , Flag Officer David Farragut ' s fleet cleared a passage through the obstructions . The fleet successfully ran past the forts on the morning of 24 April . This forced the surrender of the forts and New Orleans . The Battle of Mobile Bay on 5 August 1864 closed the last major Confederate port in the Gulf of Mexico . In December 1864 , Union Secretary of the Navy Gideon Welles sent a force against Fort Fisher , which protected the Confederate ' s access to the Atlantic from Wilmington , North Carolina , the last open Confederate port . The first attack failed , but with a change in tactics ( and Union generals ) , the fort fell in January 1865 , closing the last major Confederate port . As the Union fleet grew in size , speed and sophistication , more ports came under Federal control . After 1862 , only three ports — Wilmington , North Carolina ; Charleston , South Carolina ; and Mobile , Alabama — remained open for the 75 - 100 blockade runners in business . Charleston was shut down by Admiral John A . Dahlgren ' s South Atlantic Blockading Squadron in 1863 . Mobile Bay was captured in August 1864 by Admiral David Farragut . Blockade runners faced an increasing risk of capture — in 1861 and 1862 , one sortie in 9 ended in capture ; in 1863 and 1864 , one in 3 . By war ' s end , imports had been choked to a trickle as the number of captures came to 50 % of the sorties . Some 1 , 100 blockade runners were captured ( and another 300 destroyed ) . British investors frequently made the mistake of reinvesting their profits in the trade ; when the war ended they were stuck with useless ships and rapidly depreciating cotton . In the final accounting , perhaps half the investors took a profit , and half a loss . The Union victory at Vicksburg , Mississippi , in July 1863 opened up the Mississippi River and effectively cut off the western Confederacy as a source of troops and supplies . The fall of Fort Fisher and the city of Wilmington , North Carolina , early in 1865 closed the last major port for blockade runners , and in quick succession Richmond was evacuated , the Army of Northern Virginia disintegrated , and General Lee surrendered . Thus , most economists give the Union blockade a prominent role in the outcome of the war . ( Elekund , 2004 ) Squadrons . The Union naval ships enforcing the blockade were divided into squadrons based on their area of operation . Atlantic Blockading Squadron . The Atlantic Blockading Squadron was a unit of the United States Navy created in the early days of the American Civil War to enforce a blockade of the ports of the Confederate States . It was formed in 1861 and split up the same year for the creation of the North Atlantic Blockading Squadron and the South Atlantic Blockading Squadron . North Atlantic Blockading Squadron . The North Atlantic Blockading Squadron was based at Hampton Roads , Virginia , and was tasked with coverage of Virginia and North Carolina . Its official range of operation was from the Potomac River to Cape Fear in North Carolina . It was tasked primarily with preventing Confederate ships from supplying troops and with supporting Union troops . It was created when the Atlantic Blockading Squadron was split between the North and South Atlantic Blockading Squadrons on 29 October 1861 . After the end of the war , the squadron was merged into the Atlantic Squadron on 25 July 1865 . South Atlantic Blockading Squadron . The South Atlantic Blockading Squadron was tasked primarily with preventing Confederate ships from supplying troops and with supporting Union troops operating between Cape Henry in Virginia down to Key West in Florida . It was created when the Atlantic Blockading Squadron was split between the North and South Atlantic Blockading Squadrons on 29 October 1861 . After the end of the war , the squadron was merged into the Atlantic Squadron on 25 July 1865 . Gulf Blockading Squadron . The Gulf Blockading Squadron was a squadron of the United States Navy in the early part of the War , patrolling from Key West to the Mexican border . The squadron was the largest in operation . It was split into the East and West Gulf Blockading Squadrons in early 1862 for more efficiency . East Gulf Blockading Squadron . The East Gulf Blockading Squadron , assigned the Florida coast from east of Pensacola to Cape Canaveral , was a minor command . West Gulf Blockading Squadron . The West Gulf Blockading Squadron was tasked primarily with preventing Confederate ships from supplying troops and with supporting Union troops along the western half of the Gulf Coast , from the mouth of the Mississippi to the Rio Grande and south , beyond the border with Mexico . It was created early in 1862 when the Gulf Blockading Squadron was split between the East and West . This unit was the main military force deployed by the Union in the capture and brief occupation of Galveston , Texas in 1862 .