Lincoln’s blockade of Southern ports was initially a propaganda device intended to discourage foreign recognition and trade with the American South, and its effectiveness through 1865 was largely exaggerated. Confederate Secretary of State Judah P. Benjamin’s diplomats regularly advised foreign leaders of the increasing volume of Southern trade in an out of its ports, and despite the so-called blockade by Lincoln’s navy.
Bernhard Thuersam, www.circa1865.org
Ineffective Blockade of Southern Ports
From Mr. Benjamin, Secretary of State, Department of State, Richmond, September 2, 1863
Hon. John Slidell, etc., Paris, France
“Sir: Although it is painfully apparent that but little hope can be entertained of present redress for the injury suffered by this confederacy in consequence of the respect accorded by neutral nations to the so-called blockade of our entire coast proclaimed by the United States, it is none the less deemed a duty to renew the oft-repeated protests of this Government, lest silence be construed into acquiescence of the principles and policy avowed by one of the maritime powers of Europe, and tacitly adopted by all others.
Can the Governments of Europe justly expect that we shall continue to permit their vessels to convey without question the property of our enemies, while their lawful commerce with us remains obstructed and embarrassed by their acquiescence in the flagrant violation of public law committed by the unscrupulous people who are warring against us?
The reports of the [US] Secretary of the Navy of the United States made to President Lincoln on the 4th of July and 2nd September 1861, show that at the date of that President’s inauguration, on the 4th of March, 1861, the total number of vessels of the United States of all classes in commission was twenty-four, of which half were in distant seas; and that of the home squadron, consisting of twelve vessels, only four were immediately accessible to orders.
It results from these statements that the United States were provided on the average with one vessel for every three hundred miles of the coast, or one vessel for every fifteen of the ports of which they proclaimed the blockade. Such was the blockade at its inception. [Just] the returns from [the ports of Charleston and Wilmington] from July 1861, [to 13 August 1863]…exhibit a trade constantly and largely progressive in spite of the additions made to the Federal naval forces since the inception of the blockade.
Turning now to the port of Wilmington, we find a progressive monthly increase in the cotton exported from 526,824 pounds in January, 1863, to 2,144,887 pounds in July; while in the present month of August  these exports are likely to reach 4,000,000 pounds, if we may judge from the reports of the first thirteen days of the month.
The average foreign commerce of the port, estimate on the same basis as Charleston, is about $270,000 a month, exclusive of large quantities of naval stores. This commerce at the present rate, therefore, without allowing anything for its rapid increase, amounts to $3,240,000 per annum; while the whole foreign commerce of the State of North Carolina, including the ports of Edenton, Plymouth, Newbern, Washington, Beaufort, and Wilmington, in the year 1858 amounted to only $715,488.
Thus one “blocked” port in 1863 carried on more than four times the amount of the whole foreign commerce of the States in 1858, and this business is done by ocean steamers running almost with the regularity of packets. In January last this Government determined to introduce some supplies and to export some cotton on its own vessels, and for that purpose purchased a few ocean steamers. The report shows that these steamers have made since January forty-four voyages through the “blockading fleet” without suffering a single loss by capture. No comment can add to the force of this statement.
I am, very respectfully, your obedient servant, J. P. Benjamin, Secretary of State”
(Messages and Papers of the Confederacy, Including the Diplomatic Correspondence (excerpt), Vol. II, James D. Richardson, US Publishing Company, 1905, pp. 547-550)