American Civil War: The Blockade and the War at Sea

Back: Sherman's March through the Confederacy

The Blockage
Commerce Raiders
Battle of the Ironclads

The Blockage

One of the great ironies of the American Civil War was the Union blockade of Southern ports. In previous conflicts, the United States had stood firmly against the right of belligerent parties to impose a blockade on neutral shipping. The issue had even played a part in the outbreak of the War of 1812.

Now it was the United States that wanted to impose a blockade. President Lincoln very quickly declared a blockade against the main Confederate ports. To be a legal blockade (under the terms of an international treaty that the United States had not signed!), this blockade simply had to present a risk to shipping trying to enter those ports. This was fortunate for the Union, as when war broke out the United States navy was just as small as the army, and its ships were scattered around the world. Of those ships in American waters, ten were destroyed (or partially destroyed) to prevent them falling into Confederate hands when Virginian seceded, taking the Norfolk naval base with it.

Confederate diplomats spent much of their time attempting to convince European powers, especially Great Britain, to declare the blockade illegal. Their hope was that British industries dependence on Southern cotton would force the hands of the British government. In 1861 they were so convinced of the power of ‘King Cotton’ that the south imposed a cotton embargo, voluntarily cutting off its own best supply of money!

Ironically, the determined Confederate attempts to get Britain to declare against the blockade played a part in convincing her that the blockade was indeed effective. If it had been as leaky as the Confederates were claiming, then why make so much fuss?  Great Britain was perfectly happy to declare the Union blockade legal – the inconvenience to British trade was more than balanced by the invaluable precedent thus created.

The blockade of 1861 was indeed very leaky. Estimates suggest that only one in ten ships attempting to trade with the South was captured in the first year of the war. However, as the war progressed and the Union navy increased in size, the blockade became increasingly effective. By 1864 one in three ships were being captured, although even that ratio still left a good chance of profit for the owner of a blockade runner.

Despite claims to the contrary then and since, the blockade was effective. The number of ships entering southern ports was reduced by two thirds. Many of those ships were custom built blockade runners, capable of carrying much smaller cargos that their pre-war equivalents, so the actual amount of cargo carried must have been even smaller. The outgoing figures for cotton exports support this idea. In the three years before the war, ten million bales of cotton were exported from the south. In the three wartime years after the South lifted its own cotton embargo only half a million bales got out. While some of this was probably due to the disruption of the South’s poor transport network and the capture by the Union of ports such as New Orleans, it does demonstrate the effectiveness of the blockade.

Of course the best way to close a Southern port was to capture it. The United States Navy retained command of the seas around the Confederacy, despite repeated Confederate efforts to break that control (see below for the battle of the Ironclads). This meant that the Union could launch attacks on any Southern port that was not protected by a major Confederate army.

At the start of the war, the Confederate states contained eight major ports capable of conducting a significant amount of trade. On the east coast were Norfolk, Wilmington, Charleston and Savannah and on the Gulf coast Pensacola, Mobile, New Orleans and Galveston.

Pensacola, Florida

The port of Pensacola nearly played a major role in the succession crisis. Only its isolated position at the western end of the Florida panhandle kept it out of the secessionist limelight. One of the four Federal bases still in Union hands when Lincoln became President was Fort Pickens, in Pensacola Bay (Fort Sumter at Charleston was another).

Fort Pickens was less vulnerable to Confederate attack than Sumter. The island could be safely reinforced or re-supplied without coming in range of land based guns. While the secession crisis developed further north, at Fort Pickens it was agreed that the Union navy would be allowed to ship in supplies but not reinforcements. This agreement held until March 15, when orders were given to send in reinforcements. The Fort was successfully held by Union forces through the war, blocking Pensacola.

New Orleans (April 1862)

New Orleans was the biggest city in the Confederacy and as the sea port of the Mississippi river was also the biggest port. Her defence should have been one of the Confederacy’s highest priority, but early in 1862 the majority of her defenders were sent north in a vain attempt to push back the Union advance into Kentucky and Tennessee. On 6-7 April those troops were part of the Confederate army defeated at Shiloh.

Behind them they left 3,000 militia and a fleet of gunboats. They took this risk because they were confident that Fort Jackson and Fort St. Philip, seventy-five miles down river from New Orleans, would be able to sink any invading fleet.

If they had only faced the sailing ships that such forts had been designed to defeat after the war of 1812, then their 126 guns might well have proved enough, but time had moved on (in any case, skilled naval commanders had often overcome land based defences in earlier conflicts).

New Orleans’s fortifications were not the only connection to the War of 1812. Flag-Officer David G. Farragut, commander of the Union expedition, first joined the navy aged nine, just in time to fight in that war. Farragut was an example of Lincoln’s willingness to employ loyal Southerners. Tennessee born and married to a Virginian, Farragut was not about to desert his country.

He was just the right person for the attack on New Orleans. The mouth of the Mississippi was too shallow for large warships, so his fleet contained sloops, gunboats and schooners, smaller ships with smaller drafts, supported by 15,000 troops. At first he used mortar ships to bombard the Confederate forts, but after six days it was clear that the mortars weren’t working, and on 24 April Farragut steamed his fleet past the forts. Thirteen of seventeen ships ran the gauntlet successfully. The next day, Farragut’s fleet anchored off the now undefended New Orleans. There then following a comic-opera scene – no one could be found willing to surrender the city. Finally, on 29 April, Farragut got tired of waiting, and occupied the city’s main buildings (a desire to take the surrender before the army arrived may also have played a part).

Norfolk, Virginia (10 May 1862)

Norfolk was more important as a major U.S. Navy base than as a trading port. Its location at the end of a bay opening on to the Hampton Roads made it easy for the Union navy to blockade, especially as the Union retained control of Fort Monroe on the opposite shore of the roads. Norfolk was most famous as the home of the C.S.S. Virginia, the first ironclad warship to see combat (see below).

Norfolk was abandoned without good cause by both Union and Confederate forces. After the secession of Virginia, the Union commander of the naval base pulled out after destroying the ships present in the base (ten ships were present, although only four were modern warships – one was the U.S.S. United States, famous veteran of the War of 1812!). One of those ships was the U.S.S. Merrimack, whose hull was later used as the basis of the Virginia.

The Confederate occupation of Norfolk was ended by another survivor the War of 1812. McClellan’s Peninsular Campaign of 1862 left Norfolk vulnerable. The commander of the garrison at Fort Monroe, General John E. Wool, was another veteran of the War of 1812. While McClellan dithered on the Peninsular, Wool launched an attack on Norfolk. This time it was the Confederate commander who withdrew, so suddenly that the crew of the C.S.S. Virginia only found out when they saw the Confederate flag had been lowered. This time the Union occupation was permanent. The Virginia was now trapped without access to a port, and after a failed attempt to run upstream she was destroyed by her own crew.

Mobile, Alabama (August 1864)

The state of Alabama touches the sea around Mobile Bay, at the mouth of the Alabama River. The port of Mobile is at the head of the bay, some thirty miles from the open sea. Access to Mobile Bay was protected by three strong forts, a minefield (mines were then known as torpedoes), and by a Confederate fleet led by the C.S.S. Tennessee, a giant ironclad ram with a fearsome reputation.

The Union attack on these defences was commanded by David Farragut, already known for the capture of New Orleans, and about to add considerably to his fame. On 5 August 1864 he led his fleet of 4 monitor class ironclads and fourteen wooden ships into the bay. As the smoke from his ship obscured his view, the elderly Farragut climbed to the top of his main mast, where he was tied to the mast to prevent his being tossed overboard during the battle. From his new vantage point he gained a clearer view of his fleet’s progress.

As the Union ship passed through the bay, the first ironclad hit a mine and sank. The fleet came to a halt. Farragut ordered it to resume its progress into the bay. This much is certain. Sadly, there is now some doubt as to whether Farragut ever said ‘Damn the torpedoes! Full speed ahead’, but he will forever be known for that phrase.

Whatever Farragut actually said, his fleet successfully entered the bay. There they faced the dreaded C.S.S. Tennessee, but the giant ironclad was too unwieldy to be used as a ram, and was sunk by Union gunfire without striking a blow. With his fleet safely inside the bay, Farragut was now able to turn against the forts. The fleet was accompanied by a division of troops, who over the next three weeks captured the forts. Although Mobile itself was not captured until 1865, it was no longer usable as a port. The Confederacy had lost its last Gulf coast port east of the Mississippi.

Savannah, Georgia, December 1864

Sherman’s march through the Confederacy saw the occupation of three Confederate ports. Savannah was the first to fall to his troops. It was the target of his ‘March to the Sea’, and was also to be the launching point for the invasion of South Carolina. Sherman’s army reached the coast in mid-December 1864. On 17 December he offered surrender terms, but the garrison managed to slip away on 20-21 December. On 22 December, Sherman was able to report the capture of Savannah.

Wilmington, North Carolina, January-February 1865

Wilmington may have been one of the few Southern ports to benefit from the blockade. It stayed open longer than the other main Confederate ports. The approaches to the port were guarded by Fort Fisher at the mouth of the Cape Fear River. As long as Fort Fisher remained in Confederate hands, Wilmington would remain open for the blockade runners. It also had the most secure rail link to Petersburg and Richmond. The northern end of that railroad, the Weldon and Petersburg, was cut in August 1864, and Grant’s attempts to sever the final rail link, west along the Southside Rail Road was to become one of the main Union objectives for the rest of the war.

The capture of Wilmington was considered to be crucial to the success of Sherman’s march through the Carolinas, where his army was expected to have more trouble finding supplies than in Georgia.  The first attempt to capture Fort Fisher was made in December 1864. General Ben Butler, one of the more long-lasting of the political generals, hoped to destroy the fort with the aid of a bomb-vessel. After this attack failed, Butler was finally retired.

A second expedition, under General Alfred Terry, tried a rather more traditional assault, and on 15 January Fort Fisher was captured. Wilmington was no longer usable by the blockade runners. The last source of overseas supplies to Lee’s army around Richmond was cut. Just over a month later, on 22 February 1865, the port itself was captured.

Charleston, South Carolina, February 1865

The seat of secession held out almost until the end. Once again it was Sherman’s march to the sea that resulted in the capture of Charleston. However, the port’s usefulness came to a rather earlier end.

The first Union attack on the port ended in failure. Admiral Du Pont, commanding a fleet of nine ironclads, was sent to attack the port. He did not expect to succeed. He had won a previous success against strong land based defences at Port Royal, but there he had been able to use the mobility of his ships to overcome the normal vulnerability of ships when faced with strong land based guns. At Charleston, the narrow entrance to the port meant that he would have to stand and fight. As he expected, the forts of Charleston pummelled his ships, and in under two hours forced the Union ironclads to withdraw.

This dramatic failure had been followed by two years of Union blockade and bombardment. Federal forces had occupied several coastal islands off the coast of South Carolina, from where they were able to mount repeated attacks on the forts. Fort Sumter, where the first shots were fired, was destroyed by Union guns, but still Charleston held out.

In the end, Charleston had to be abandoned on 17 February 1865, not because of a direct threat, but because of Sherman’s army, fifty miles distant, but about to cut Charleston’s lines of communication to the rest of the Confederacy.  

Galveston, Texas

The only major port west of the Mississippi, Galveston lost its significance for most of the Confederacy on 4 July 1863, when the fall of Vicksburg closed the Mississippi to Southern trade. The city briefly fell to a Union naval expedition in October 1862, but a second expedition at the end of December 1862 ended in an embarrassing repulse for a combined Army-Navy expedition.  The trans-Mississippi Confederacy was soon cut off, but was the last area to surrender in 1865.

Commerce Raiders

Blockade is an option only realistically available to the stronger naval power. If the weaker naval power wants to disrupt their opponent’s seaborne trade, then their only realistic hope was the privateer or commerce raider (privateers are normally privately owned and commerce raiders government owned). The most famous example of the commerce raider is the U-boat, which came close to cutting Britain’s transatlantic lifeline during the Second World War.

The Confederacy also resorted to the commerce raider. The nineteenth century commerce raider was not the indiscriminate killer of later periods. The rules of war required the commerce raider to take the crew off any captured ship before either sailing it to a friendly port or sinking it, and Confederate commerce raiders stuck to these rules.

The biggest problem facing the Confederacy was lack of suitable ship building facilities in the south. Early commerce raiders, such as the C.S.S Sumter, were ad-hoc affairs, although that ship had some success. The Confederacy’s best hope of creating a deep water navy came from Britain. At the outbreak of war, the Confederacy had some support amongst members of the British government, but never enough to gain official recognition of their cause.

In 1862 the Confederate agent in Britain, James D. Bulloch, achieved his most famous success with the launch of the ship that was to become the C.S.S. Alabama. However, this success did not indicate British approval of his efforts, but rather a lack of urgency on the part of the British. The following year the British government was forced to take a firm stance by the near-completion of two powerful ironclad rams. On 5 September 1863 the British foreign secretary, Lord John Russell, issued orders to detain the rams. The Confederacy would have to cope with the ships already at sea.

The most famous of those ships was the C.S.S Alabama, commanded by Captain Semmes, formerly of the Sumter. Between her launch on 22 July 1862 and her destruction on 19 June 1864, she captured or sank sixty five northern ships. She was finally sunk by the U.S.S. Kearsarge after a short duel apparently brought on by Captain Semmes’s bruised pride and determination to prove that his ship was a genuine warship and not just a commerce raider!

Although the commerce raiders had little impact on the outcome of the war, they did immeasurable damage to the American merchant marine. In 1860 the American fleet was well on its way to overtaking the British as the biggest in the world, but four years of commerce raiders persuaded so many American ships to change nationality that the merchant fleet never regained its former size.

Battle of the Ironclads

The most famous naval clash of the war was the Battle of the Hampton Roads. Steam power was already in the process of revolutionizing war at sea. Exploding shells were replacing solid shot. The world’s main navies had been experimenting with iron armour. The Crimean War had seen the French navy use armoured floating gun batteries and exploding shells to devastating effect against the wooden Russian ships.

The first ironclad warship was the French Gloire of 1859, followed quickly by the British H.M.S. Warrior. The United States navy had been watching these developments, but had not yet moved towards building their own ironclads when the civil war broke out. In the first few months of the war experiment warships naturally moved to the bottom of the U.S Navy’s list of priorities.

In contrast, the newly formed Confederate navy needed some way to overcome the vastly superior Union numbers. They looked to the new ironclads for their answer. If the south could build a functioning ironclad warship before the Union, they hoped that they could smash the Union blockade and impose their own blockade in turn.

When the Union navy abandoned Norfolk, Virginia, they attempted to destroy the ships stationed there. One of those ships was the frigate U.S.S. Merrimac. In the summer of 1861, the Confederates raised the sunken frigate, and began work converting it into an ironclad warship, the C.S.S. Virginia. Their plans were dramatic. The 264-foot long frigate was cut down to the berth-deck. This deck would be just under water in normal circumstances, with armour plating covering the top three feet of the hull. On top of this was built a 170 foot long pent-house, with sloped armoured sides, containing 7-inch pivot guns to front and rear as well as four guns in each broadside.

Unfortunately for their plans, news of their work reached the north. Two conventional designs were initially approved, but they would not have been ready in time to counter the Confederate ship. A third plan, designed by the inventor John Ericsson, was adopted in October 1861. His design was revolutionary. The U.S.S. Monitor resembled an armoured raft, 172 feet long, with a deck only just above water level. What made the Monitor so revolutionary was that all of her firepower came from two eleven inch guns in a revolving turret.

The two ships would turn out to be very well matched. The C.S.S Virginia got her chance first. On 8 March 1862 she steamed out of Norfolk to attack the Union blockading fleet. Her ten guns were opposed to 219 Union guns on five ships, but the Union ships didn’t stand a chance. First to go was the U.S.S. Cumberland (24 guns), rammed and sunk. The only serious damage inflicted to the Virginiawas that her ram broke off and remained stuck in the Cumberland.

Next, the Virginia turned on the U.S.S. Congress, a fifty gun sail frigate. Her wooden sides were of no use against modern guns. She caught fire and sank. The Virginia returned to harbour, expecting to finish the job the next day. The U.S.S. Minnesota, a new steam frigate, ran aground during the encounter and unless help came quickly would certainly be sunk on the following day.

That help did arrive. Overnight the U.S.S. Monitor had arrived from New York. The next day the two ships engaged in the first duel between ironclad warships. The fighting on 9 March was a tactical draw. Neither ironclad could inflict significant damage on the other. Eventually, the Monitor pulled back into shallower water than the Virginia could enter. While the Monitor was unable to sink the Virginia, the Confederate ship could not damage the remaining Union ships. The Union navy would be able to maintain her blockade.

The battle of the ironclads sent shockwaves around the world’s navies. The Times of London announced that the Royal Navy had been reduced from one hundred and forty nine to only two first class warships. Britain and France were both forced to almost totally rebuild their navies. Every wooden warship in the world became obsolete overnight.

Next: The West

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A Great Civil WarA Great Civil War, Russel F. Wiegley, Indiana University Press, 2004, 648 pages. This is a superb account of the civil war years. Weigley has produced a book that combines a good understanding of the military aspects of the war with a clear grasp of the wider issues at stake. [see more]
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How to cite this article: Rickard, J (1 May 2006), American Civil War: The Blockade and the War at Sea ,

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