A key part of Abraham Lincoln's military strategy rested upon an effective blockade of the South's 3,500 miles of shoreline, including a dozen major ports and nearly two hundred inlets, bays, and navigable rivers. This was an almost impossible task for a nation with only a handful of naval ships. By the war's end, however, Lincoln had commissioned about five hundred ships, with an average of 150 on patrol at any one time. These ships captured or destroyed approximately fifteen hundred blockade runners. On the other hand, five out of six blockade runners evaded capture, enough to allow Britain to argue that it was a "paper blockade" not recognizable by international law. Most of this cargo, however, was lightweight luxury items, small munitions, and medicines. On the export side, the Confederacy shipped but a small percentage of its cash-earning cotton crop abroad during the war, five hundred thousand bales compared to ten million bales for the three years prior to the start of the Civil War.

Foreign Recognition and Intervention in the War

The issue of the blockade's effectiveness became the major foreign policy question in the first few years of the war. The Confederacy confidently expected England to escort Confederate cotton vessels or to send British merchant and war ships to Southern ports to pick up vitally needed cotton. To hasten this active intervention, the Confederacy informally cut off most cotton exports in 1861. Surprisingly, England took no official action to break the blockade and even tolerated the seizure by the Union of British ships trading with the Confederacy. Nor did England ever officially extend diplomatic recognition to the Confederacy.

This is not to say that the failure of England and other European countries officially to support the Confederacy was a foregone conclusion. Nor is it to say that no aid was extended from England to the Confederate war effort. Far from it. At several times during the war, both England and France came close to recognition and to intervention. It took all the skill of America's minister to England, Charles Francis Adams, the grandson of President John Adams and the son of President John Quincy Adams, to keep England out of the war.

Southern Belligerency Status

The first crisis occurred when England issued a proclamation of neutrality, which rested upon the logic of the Union's declared blockade. According to English reasoning, although Lincoln proclaimed the rebels to be insurrectionists and thus not recognizable under international law as a belligerent power engaged in war, his declared blockade was an act of war, which would have to be conducted against a sovereign state. Thus Lincoln had actually granted belligerency status to the Confederacy and thereby forced foreign powers to do the same. By proclaiming neutrality, England afforded the Confederacy the status of a belligerent power. Other European nations followed England's lead. Belligerency status gave the Confederacy the right, according to international law (signed by European nations after the Crimean War in 1856), to contract loans and to purchase arms from neutral nations. It also allowed England to provide safe harbors for both Union and Confederate warships and merchant vessels, to build blockade runners and warships for the Confederacy, and to formally debate in Parliament the merits of active intervention.

The delicacy of the situation exploded into near battle when two Confederate diplomats, James Mason and John Slidell, were seized by the U.S. Navy from a British ship, the Trent, en route to England. England's prime minister, Lord Palmerston, sent Lincoln an ultimatum demanding an apology and the release of Mason and Slidell, and ordered troops to Canada in preparation for war. He also seized all English shipments to the U.S., including a vital supply of saltpeter, the principal ingredient of gunpowder, of which the Union was in desperately low supply. Lincoln had little choice but to release Mason and Slidell, although he avoided a public apology. England, greatly relieved, refused to press the issue.

For the remainder of the war, English shipbuilders constructed dozens of lightweight blockade runners for the Confederacy as well as several warships. The C.S.S. Alabama and Florida sunk sixty-four American merchant ships in the course of the war. In France, Louis Napoleon sent thousands of French soldiers into Mexico to overthrow the regime of Benito Juérez in hopes of making the nation a French colony. He unofficially supported the Confederacy but stopped short of formal recognition. In the summer of 1862, a coalition of European nations—Britain, France, Russia, Austria, and Prussia—came close to offering to mediate the war, which would have been tantamount to recognizing Confederate independence.

In the end, however, no European nation offered mediation nor extended recognition of the Confederacy. Among the reasons undermining active European intervention were several principal considerations. Economically, there were developments that shifted trade relations to emphasize the North's economic ties with Europe. To begin with, huge cotton exports in 1857-1860 had enabled English manufactures to stockpile inventories that carried them through much of the war. Additionally, new sources of cotton in Egypt and India replaced the Southern supply after 1862. Furthermore, the Union became a major consumer of British iron, ships, armaments, and woolen uniforms and blankets, which absorbed the decline in the U.S. market for English cotton textiles. At the same time, crop failures in Western Europe in 1861 and 1862 increased European dependence on American grain and flour, making King Corn as powerful as King Cotton.

Socially, the open hostility of England's working class to the Confederacy as a nation of aristocrats and slavemasters countered the support for the Confederacy by English members of the upper class. Lincoln's Emancipation Proclamation served to transform British antislavery sentiment into strong political opposition to the Confederacy. On the diplomatic front, there was a delicate balancing act between France and England, as neither side wanted to be the first to recognize Confederate independence lest the other use it to foment a new alliance with the Union.

All of these factors came to play in a series of diplomatic flourishes and sentiment shifts that reflected the battlefield fortunes of Union armies. But nothing was perhaps more consequential than the effect of the Emancipation Proclamation when combined with Lincoln's iron determination to win the war. Once the war became a crusade to destroy slavery, and once the Union Army presented itself as an army of liberation, rather than just an army of national self-preservation, it was almost impossible for England to intervene on the side of the Confederacy. British public opinion had become strongly abolitionist, and no government could have taken the other side.