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Blockading the American Confederacy, 1861-1865:
A Geo-Strategic Analysis

by Hardy, Jr., James D. and Hochberg, Leonard J. Issue: Spring 2006

A paper to be included in a volume devoted to the comparison to the comparative history of blockages, edited by Professor Jean-David Avenal.


Blockade, as a formal and systematic weapon in modern naval warfare, distinct from battle and maneuver, developed during the Napoleonic wars and was further refined by the Royal Navy in its decades-long campaign after 1815 to suppress the African slave trade (1). In spite of this extensive history, it was not until the Treaty of Paris ending the Crimean War that a Declaration Respecting Maritime Law, dated April 16, 1856, formally established the general principles of international law that would define blockade and abolish privateering, blockade's traditional response. Blockades were described in four short articles:

1. Privateering is, and remains, abolished;

2. The neutral flag covers enemy's goods, with the exception of contraband goods;

3. Neutral goods, with the exception of contraband war, are not liable to capture under enemy's flag;

4. Blockades, in order to be binding, must be effective, that is to say, maintained by a force sufficient really to prevent access to the coast of the enemy (2).

The Declaration of 1856 envisioned naval activity in terms of three simple categories, men-of-war, merchant vessels, and the now illegal privateers, or commerce raiders. There categories had been formed by centuries of experience with sailing ships made of wood, armed with cannon effective in terms of yards. The blockade itself was sailing squadrons patrolling seaports. Contraband of war was thought of as guns and ammunition, while other stock in trade was regarded as ordinary commerce and exempt from seizure. Neutrals were recognized governments that had not declared war. The Declaration made everything perfectly clear in law and fact.

Steam power and metallurgical technology were altering all this, but the Declaration declared principles on the basis of continuity, of what was known, rather than change, or what was merely imagined. The diplomats and admirals in Paris also assumed that Britannia would continue to rule the waves and that naval war in Europe was unlikely, making the principles of the Declaration applicable into the indefinite future. But the principles of 1856 were soon to be tested on all the world's oceans by an unexpected conflict, the American Civil War, an were to be upheld by diplomacy and international law in the Geneva Tribunal of Arbitration (1872) after they had been found simplistic and obsolete by the experience of war.

Origins of the Civil War Blockade

Although the United States of America was not a signatory to the Declaration Respecting Maritime Law, negotiations in the spring of 1861 between Washington and London (and Paris) concerning the maritime implications of secession and Civil War proceeded upon the principles contained therein. The initial issues, from March to May, 1861, involved the British recognition of rebellion and belligerency in the Confederacy, along with the refusal of the British and the French to give formal diplomatic recognition of the Confederacy. The question of recognition led immediately to discussion of issues of blockade and privateering. Have no navy, the Confederate President, Jefferson Davis, turned to commerce raiding as a way of confronting the Union at sea. In April, 1861, Davis issued letters of marquee and reprisal, placing his regime in direct opposition to the Declaration of 1856. President Lincoln proclaimed the southern privateers to be pirates, which, in the absence of formal diplomatic recognition of the Confederacy by major foreign governments, was not entirely inaccurate description of their status. On April 20, 1861, a week after the Confederate shelling of Fort Sumter, President Lincoln extended war at sea by announcing a blockade on Southern ports (4). This placed the American government within the spirit of the Declaration, though questions remained as to whether the Union blockade in the summer and fall of 1861 fell within the definition of a real impediment to trade (5), or was merely a paper blockade. Nevertheless, the Union intent was clear. The United States would adhere to the Declaration of 1856 and would demand that other powers did as well.

Nature of the Blockade

Once established during the summer of 1861, the Union blockade of the Confederacy became an instrument of geo-strategy that was far more sophisticated than the mere presence of naval squadrons envisioned by the signatories to the Declaration. The American blockade, over the course of 1861 to 1862, came to consist of four distinct levels of interdiction of Southern commerce and naval warfare. The first level was a systematic effort beginning in 1862, to conquer the Confederate littoral, including rivers and seaports. Troops landed on the Carolina coast and occupied ports and towns, and a naval squadron ascended the Mississippi River, capturing New Orleans, Baton Rouge, and Natchez, thus closing the main pre-war artery of Southern Commerce (6). The second level involved naval squadrons blockading the coastal sea lanes in the traditional manner. Few and scattered in 1861, these squadrons commanded the still unconquered stretches of Southern coast by 1863 (7). The few southern ports that remained open in the autumn of 1863, primarily Mobile, Alabama, Charleston, South Carolina, and Wilmington, North Carolina, were sufficiently patrolled that only the swiftest and most daring runners made it through the Union squadrons. Even when successful, blockade running could not supply the import needs of a regional economy, nor get enough cotton abroad to support the Confederacy at home. The first two levels of the Union blockade had cut the Confederacy off from the world in less than 20 months.

The third level and fourth levels of the Union blockade operated on a world stage as opposed to being concentrated on and close to the southern shore. The third level consisted of warships roaming the oceans searching for Confederate commerce raiders, such as the Alabama. This element of the blockade was designed to eliminate offensive Confederate naval warfare, which had the effect of driving marine insurance rates in increased war premiums to levels that threatened to choke off Union commerce (8). Finally, a fourth level of blockade, consisting of diplomatic and intelligence services, was established in Great Britain and France to prevent Confederate ship-building abroad (9). Although the weight of the Union effort in these two levels of blockade resided in intelligence and diplomacy rather than invasion, and in cruisers rather than fleets, the result was the same. By the beginning of 1864, Confederate efforts to gain naval foothold in Europe or drive Union commerce from the high seas, were clearly failing, the result of Union victories in America and the cautions calculation of European governments.

This multi-level blockade was something new in naval warfare, but by 1864, it had succeeded in destroying Confederate capacity to engage in foreign commerce or wage naval warfare (10). It also demonstrated how complex a geo-strategic weapon, combining military, diplomatic, commercial and intelligence components, an effective naval blockade had become (and had to become) in an industrial age. Blockades had transcended the ships at sea and encompassed civilian concerns of commerce, industry and finance, as well as wider military efforts of intelligence, diplomacy, and technology.

The Union Blockade: Land and Sea

Although the Carolina coastal campaigns closed several smaller Southern ports, the most important strategic imitative undertaken by the Union involving the first two levels of blockade was the Mississippi River campaign in 1862 which closed the major artery of southern commerce. New Orleans was the leading southern port in 1860, as the steamboat technology funneled the produce of the entire mid-continent down the river to the Crescent City (11). Since there were numerous bayous and mouths of the river that connected the Mississippi to the sea, the requirement of the blockade meant that the Union must capture New Orleans and control both the river and the coast. To that end, the Union launched a combined arms campaign, involving a fleet moving up the Mississippi to run the down-river forts of Jackson and St. Phillip and an army to occupy New Orleans and its environs after the fleet had closed the river to Confederate traffic.

The river fortresses, Jackson and St. Phillip, had been designed in the generation before the Civil War, when land-based cannons outgunned shipboard ordnance, and steam engines were barely able to propel men of war upriver against the stiff Mississippi current. At the time, in the 1830s, the forts had seemed adequate to the task of protecting New Orleans, but by 1862, naval technology, both in cannon and engines, had shifted the advantage from forts to ships. The forts were the only defense New Orleans possessed. Built up to its levies, which were lined with docks and warehouse, the city was entirely vulnerable to cannon fire. If the blockading fleet ran the forts, surrender and occupation were the only option available to New Orleans.

So important was New Orleans to the commercial life of the Confederacy that its capture on April 25, 1862, decisively altered the first two levels of the blockade to the Union advantage. Occupation of New Orleans added the river fleets to the Ocean blockade, transforming the blockade from a largely passive commercial interdiction into part of the military effort to occupy the Confederacy and end the war. The war at sea became joined, on the rivers, with the war on land. Moreover, the capture of New Orleans opened the lower Mississippi valley to Union commerce. The plantations along the Mississippi had no choice but to continue to ship their cash crops, primarily cotton and sugar, to New Orleans, where that helped sustain the Union economy rather than sustaining the Confederacy (12). With the conquest of New Orleans, geo-economics joined geo-strategy simultaneously producing a decisive Union victory through redirecting the commerce of the Mississippi to the benefit of the Union.

The capture of New Orleans instantly added a strategic dimension to another combined arms campaign that had already moved south against the Confederate river fortifications in north-western Tennessee. General U.S. Grant and Admiral Andrew Foote took Fort Henry on the lower Tennessee River on February 6, 1862, and Grant captured Fort Donaldson on the Cumberland about a week later. These victories opened the upper Mississippi to a Union advance, and it became possible to envision Union control over the entire Mississippi valley. Grant continued to move south, and captured Vicksburg, Mississippi, on July 4, 1863. Two widely separated and early successes at either end of the river, one victory associated primarily with blockade and the other with invasion of the South, came together in an 18 month campaign that cut the South in half and made a Confederate victory impossible. In the American Civil War, blockade moved in a single year from interdiction of commerce to an active instrument of conquest.

The third and fourth levels of the Union blockade, clearing the seas of commerce raiders and preventing Confederate shipbuilding abroad, were geopolitical responses to an imaginative Confederate effort to leap over the physical blockade of their coasts. Lacking the industrial infrastructure to build a navy at home, the Confederacy sought to build warships in England and France, thus attacking the Union commercial shipping on the high seas and creating a blockade of its own. The Confederate assault was primarily upon the costs of commerce, particularly driving up marine insurance rates, but these tactics were not ineffective just because they were novel. The Declaration of 1856 and Union naval strategy envisioned a physical blockade, while the Confederacy sought to counter this with a financial (and fiscal) blockade, hoping to increase the costs of trade sufficiently to drive American flag shipping into port (13). Both sought the destruction of commerce; only the means differed (14).

The key Union efforts to establish the third and fourth levels of the maritime blockade began in 1862, and were greatly expanded after their failure to prevent the C.S.S. Alabama from getting to sea. The Union legal and intelligence efforts in Europe were only beginning in May and June of 1862, and Confederate Captain James Bullock was able to slip the Alabama to sea on July 29 (15). But the Union response to this contretemps was sufficiently vigorous and sustained to limit Confederate commerce raiders built in Europe from playing a critical role on the strategic level of the war (16). It included intense diplomatic pressure on the British and French governments, an extensive intelligence effort to detect shipbuilding on the ground, and outfitting cruisers to chase down the southern commerce raiders. On the third and fourth levels of the Union blockade, military and civilian activity merged into a single campaign in which memos and meetings had become as important as sailing and shooting.

As with the blockading squadrons and coastal conquest, the Union diplomatic and cruiser blockade prevailed on the strategic level. Commerce raiding was the maritime equivalent of guerilla war on land. The Confederate raiders had some striking success, but commerce raiding exhibited all the problems inherent in irregular conflict. The raiders could not maintain consistent pressure on Union commerce, so the advantages gained proved evanescent while the Union blockade on all four levels became gradually more effective. The raiders were hunted down and destroyed, marine insurance stabilized, Union commerce regained lost ground, and European governments steadily refused to recognize the Confederacy. The Union blockade achieved its geo-strategic goal of cutting the Confederacy off from the world, and had done so by changing the nature and definition of a naval blockade from cutting a city or state off from the world to cutting the world off from a city or state.

Consequences of the Blockade: Diplomacy and Law

Blockades normally end when the war does, but the differences between the United States and Great Britain over the proper role of neutrals were too great to disappear quietly after Appomattox. The shooting in American might stop but the shouting across the Atlantic increased. The United States Senate resolved on December 4 and 10, 1867 and again on May 27, 1868 to ask the State Department to put together the Alabama Claims against Great Britain, and that was done by April 7, 1869. The Grant administration pursued these claims diplomatically, and on May 8, 1871, concluded in Washington a treaty with Great Britain to submit everything to a Tribunal of Arbitration to be convened at Geneva.

The depredations of the insurgent cruisers, the Sumter, Nashville, Florida, Alabama, Georgia, Shenandoah, Chickamauga, Tallahassee, and Retribution, reached a huge sum for the times, over nineteen millions in nineteenth century gold dollars, according to the Claims Against Great Britain submitted to the Geneva Tribunal of Arbitration (17). Money reinforced moral outrage at assumed British connivance at what Americans saw as piratical depredations upon civilians as well as costs in treasure (precisely quantified) levied upon the United States. The costs inflicted upon the United States and private merchants and banks by the Confederate efforts to leap over the shoreline blockade by finding support in Europe were too large to ignore and the irritation with the British was too deep to forgive.

The position of the American government was clear. Convinced of British sympathy for the Confederacy, which was not true, the American government regarded the huge and unexpected losses as at least partially the fault of the British. A Republican government, which was attuned to the interest of commerce and industry, was determined to push claims for compensation. The British position was more ambiguous. Though Britain defended its conduct and attitudes, the British, who would certainly be the maritime power to impose a naval blockade in the next conflict, also wanted the arbitration and diplomacy to conclude results favorable to the blockading power, which had been the United States. The British therefore were prepared to make concessions, including allowing the dispute to come to binding arbitration, which would then turn mere claims into an agreement the British would have to honor.

Arbitration moved the debate from politics to law and economics, and in 1872, the Tribunal issued its findings and began publishing its report. What matters is not the local findings, somewhat more favorable to the United States than might have been predicted, but the immense distance reality had wrought upon the simple formulations of the Declaration of 1856. In Paris in 1856, a naval blockade was seen as a simple and mechanical application of naval squadron tactics. In Geneva in 1872, a naval blockade was a complex multi-level geo-strategic activity, covering not just a coast but the whole world, involving not just ships but lawyers, insurance brokers and diplomats. Blockades had become an entire theatre of war, evolving their own tactics and specialized weapons, along with spurring innovative techniques for breaking the blockade down. What new forms these weapons, tactics and techniques would take could not be known in 1872, but it as clear that the experience of naval blockade during the American Civil War had rendered obsolete, even quaint, all the blockade experience that had gone before. The geo-strategic shadow of the Civil War experience in naval blockade proved to be more durable than almost any other aspect of conflict.


1) Paul Kennedy, Rise and Decline of British Naval Mastery; Arthur Herman, To Rule the Waves: How the British Navy Shaped the Modern World (New York: HarperCollins, 2004).


3) The basic source for the Civil War blockade is the published papers of the Geneva Tribunal of Arbitration which adjudicated the Alabama claims within the context of the British position on neutrality and belligerency during the War. These papers appear in four series. The first is the United States Claims Against Great Britain, 7 vols. (Washington: Government Printing Office [GPO], 1869-1871); the second is The Case of Great Britain, 3 vols. (Washington: GPD, 1872); the third is The Counter Case of Great Britain, 11 vols. and appendix (Washington: GPO, 1872); the fourth is Papers Relating to the Treaty of Washington, 6 vols. and appendix (Washington: GPO, 1872-1874).

4) Lord Lyons to Lord Russell, April 22, 1961, in Claims Against Great Britain, vol. 1, pp. 18-19; see also Notification of Blockade, April 20, 1861, pp. 20-21, 22-23; Lord Lyons to Lord Russell, April 27, 1861, pp. 23-24; and Lord Lyons to Lord Russell, May 4, 1861, pp. 25-26.

5) The opposite of a real blockade was a paper blockade which substituted a proclamation for actually ships at sea. Paper blockades were expressly prohibited by article 4 of the Declaration, but questions always remained as to how thin, exactly, a naval blockade had to be before it became just paper. In May, 1861, the Union actually blockaded only a few southern ports, Norfolk in Virginia and Pensacola in Florida for example, but month by month the physical blockade increased. By 1864, only three ports remained even partially opened: Mobile, Alabama; Charleston, South Carolina; and Wilmington, North Carolina.

6) For a geographic representation of this effort, see several recent atlases of the Civil War: George B. Davis, Major, U.S. Amery; Leslie J. Perry: Joseph W. Kirkley; Calvin D. Cowles, Captain, U.S. Army, The Official Military Atlas of the Civil War: Atlas to Accompany the Official Records of the Union and Confederate Armies (Washington: GPO, 1891-1895; New York: Arno Press & Barnes and Noble, 1983 and 2003), plate 12, no. 6; plate 40, nos. 3, 4; plate 24, no. 5; plate 131, no. 2; plate 90, no. 1; plate 135A; plate 24, no. 1; Mark Swanson, ed., Atlas of the Civil War: Month by Month, Major Battles and Troop Movements (Athens, Georgia: University of Georgia Press:, 2004), p. 32; Thomas E. Griess, ed., Atlas of the American Civil War: The West Point Military History Series (Garden City, New York: Square One Books, 2002), map 18; Steven E. Wadsworth and Kenneth J. Winkle, eds., Atlas of the Civil War (Oxford, UK: Oxford University Press 2004), pp. 106-108. These atlases have been reviewed by James D. Hardy, Jr. and Leonard J. Hochberg, The Cartographic Display of Geo-Strategic Information: A Review Essay of Six Civil War Atlases, The Civil War Book Review, Winter, 2005 (

7) The basic source of the naval wartime remains the Official Records of the Union and Confederate Navies in the War of the Rebellion, 30 vols. in two series (Washington: GPO, 1894-1927), known as the ORN. The three volume second series deals with naval diplomacy.

8) Claims Against Great Britain, Vol. VII, p. ccxlvii.

9) Frank J. Merli, The Alabama, British Neutrality, and the American Civil War (Bloomington, IN: Indiana University Press, 2005). Earlier scholarship, though substantial, had significant errors of fact, which indicated a strong sympathy of the South in the British government, which did not exist. See Ephraim Douglass Adams, Great Britain and the American Civil War, 2 vols. (London: Longmans, Green, and Co., 1925) and Frank L. Owsley, King Cotton Diplomacy: Foreign Relations of the Confederate States of America (Chicago, IL: University of Chicago Press, 1931). Merli's correction of this non-existent southern bias places levels three and four of the Union blockade in their proper political context. See also Frank Merli, Great Britain and the Confederate Navy (Bloomington, IN: Indiana University, 1970); Stephen R. Wise, Lifeline of the Confederacy: Blockade Running During the Civil War (Columbia, SC: University of South Carolina Press, 1988). The comments by Captain James Bullock, Theodore Roosevelt's maternal uncle Jimmy and the officer who got the Alabama to sea, are particularly instructive. James D. Bulloch, The Secret Service of the Confederate States in Europe (London: Bentley, 1883; New York: T. Yoseloff, 1959, 2001). Bulloch remained in England after the war. A good survey of the post-war diplomacy on blockades and commerce raiding is to be found in Adrian Cook, The Alabama Claims: American Politics and Anglo-American Relations, 1865-1872 (Ithaca, NY: Cornell University Press, 1975); and Charles C. Summersell, C.S.S. Alabama: Builder, Captain and Plans (University, AL: University of Alabama Press, 1985), an essential book on the ships entire history. For a nineteenth century view on the blockade, see John Russell Soley, The Blockade and the Cruisers (New York: Jack Brussell, 1883).

10) On the comparative and geo-strategic advantages of maritime versus land power, the essential book is Colin S. Gray, The Leverage of Sea Power: The Strategic Advantage pf Navies in War (New York: The Free Press, 1992). Other useful studies include Jan Glete, Navies and Nations, Warships, Navies and State Building in Europe and America, 1500-1860, 2 vols. (Stockholm: Almqvist & Wiksell International, 1993); Clark C. Reynolds, Command of the Sea: The History and Strategy of Maritime Empires (New York: William Morrow & Company, Inc., 1974); and Clark G. Reynolds, 'Thalassocracy' as a Historical Force, America as a ThalassocracyýAn Overview and :Reconsidering American Strategic History and Doctrines, in History of the Sea: Essays on Maritime Strategies (Columbia, SC: University of South Carolina Press, 1989), pp. 20-65, 77-107 and 108-136.

11) For an understanding of the shift in interregional commerce due to the building of east-west railroads in the Northern states prior to the Civil War consult John Agnew, The United States in the World-Economy: A Regional Geography (Cambridge: Cambridge University Press, 1987), pp. 95-110).

12) See Richard Follett, The Sugar Masters: Planters and Slaves in Louisiana's Cane World, 1820-1860 (Baton Rouge, LA: Louisiana State University Press, 2005) for an examination of the trade patterns and the agro-industry of Louisiana sugar cane culture.

13) On increased war premiums claimed at Geneva, see Claims Against Great Britain, vol. VII, pp. ccxxxiii-ccxliii. The losses claimed, by ship, are in the same volume, pp.iii-ccxxxii.

14) Secondary benefits from the Southern commerce raiders included pressuring American shippers to call for an end to the war and potentially reducing Union revenues derived from customs.

15) Merli, The Alabama, chapters 2-4.

16) On the voyages of the insurgent cruisers, Sumter, Nashville, Florida, Alabama, Georgia, Shenandoah, Chickamauga, Tallahassee, and Retribution, see Claims Against Great Britain, vol. VI, pp. 190-745. On the Alabama, see her captain's memoirs. Raphl Semmes, Memoirs of Service Afloat during the War between the States (Baltimore: Kelly Piet, 1868). See also Arthur Sinclair, Two Years on the Alabama (Boston: Lee and Shepard, 1895) and Charles C. Summersell, ed;, The Journal of George Townley Fullam: Boarding Officer of the Confederate Sea Raider Alabama (University, AL: Published for the Friends of the Mobile Public Library [by University of Alabama Press, 1973).

17) Vol. VII, p. ccxlvii

James D. Hardy, Jr. and Leonard J. Hochberg are professors at LSU, and are preparing a book on the geopolitics of the Civil War.

review of Blockading the American Confederacy, 1861-1865:
A Geo-Strategic Analysis
, by Hardy, Jr., James D. and Hochberg, Leonard J., Civil War Book Review, (Spring 2006).