Throughout the Civil War, the Union navy encircled the Confederacy’s ports and confiscated property that was entering or exiting the country in an effort to restrict the Confederate economy. While its full effect may be debated, it played a significant role in reducing the Confederacy’s foreign trade and consequently the strength of its economy and ability to conduct the war.
At any given time during the Civil War, there were approximately 150 ships maintaining the blockade of the Confederacy.[i] Throughout the course of the conflict, there were blockade runners at an interval of once every three or four weeks, leaving one sailor to write home recommending that if one wanted to replicate the experience: “go to the roof on a hot summer day, talk to a half-dozen degenerates, descend to the basement, drink tepid water full of iron rust, climb to the roof again, and repeat the process at intervals until fagged out, then go to bed with everything shut tight.”[ii]

As difficult as capturing a blockade runner may have been, the reward was tantalizing, as the crew shared half of the proceeds from each captured ship.[iii] After the first year of the war, the blockade had devised a system that tightened the grip on blockade runners: when a potential runner “approached the harbor entrance,” a watchman sent up rocket signals, causing Union ships to close in on the runner but leaving a “second cordon of Union ships” continuing to patrol the wider area.[iv] Detecting and pursuing the runners was not so simple: as the war progressed, vessels had a gray coat of paint, burned smokeless fuel with telescoping smokestacks, and “underwater steam-escape valves,” and when Union ships gave chase, they deployed their own signal rockets and fired them in the opposite direction of their fleeing.[v]
The stakes were high not just for the Union sailors but the blockade runners. One or two round trips with cargo could net a profit for the runners in gold (rather than the constantly devaluing Confederate money).[vi] Certain ports, like Nassau and Wilmington, boomed as hosts of the blockade running business.[vii]

By the conclusion of the war, the blockade’s effectiveness could scarcely be disputed. Although many runners made it through the blockade and to their destination, the odds of that occurring diminished by half throughout the course of the war.[viii] Because at the outset of the war nine out of ten runners made it through the blockade, and because the tightening of the flow of goods did not affect the upper echelons of Confederate society, some characterized the blockade as “old Abe’s . . . practical joke on the world” and no more than a “paper blockade.”[ix] However, even in 1861 and early 1862, ordinary Confederate men and women complained of enormous raises in prices for groceries, shoes, and other goods.[x]
While some identified the blockade’s leaks as evidence of its ineffectiveness, historians have concluded that the deterrence effect of the blockade was its most consequential as the four years of the war saw a total of 12,000 fewer trips out of southern ports than the preceding four years.[xi] The blockade’s pressure on the southern economy was one major factor in the inflation that reduced the Confederate dollar to one percent of its original value by the conclusion of the war.[xii] Its maintenance ensured that the war, being a war of resources, would always tilt in favor of the Union as it would not only have the superior manpower (manpower sufficient to leave idle sailors at sea maintaining the blockade for four years); it would also have the superior economy.
[i] See James McPherson, Battle Cry of Freedom: The Civil War Era, 378.
[ii] Richard S. West, Jr., Mr. Lincoln’s Navy (New York, 1957), 60.
[iii] See James McPherson, Battle Cry of Freedom: The Civil War Era, 378.
[iv] Id. at 379.
[v] See id.
[vi] Id. at 380.
[vii] Id. at 379-80.
[viii] Id. at 380.
[ix] Id. at 380-81 citing Frank L. Owsley, King Cotton Diplomacy: Foreign Relations of the Confederate States of America, 2nd ed. Rev. (Chicago, 1959), 229-30.
[x] James McPherson, Battle Cry of Freedom: The Civil War Era, 381.
[xi] Id. citing Howard P. Nash, Jr., A Naval History of the Civil War (New York, 1972), 300.
[xii] See James McPherson, Battle Cry of Freedom: The Civil War Era, 382.