The Union government never recognized the Confederate States as a nation or as a government. However, the proclamation of a blockade of Southern ports (April 19, 1861) had the effect of giving the Confederacy the rights of belligerents, which foreign governments immediately recognized by proclaiming neutrality. Captured Southerners were treated not as rebels or traitors, but as prisoners of war. After the war a few persons were tried for war crimes, but no charges of treason were ever brought to trial by the Union.

Although foreign governments proclaimed neutrality, they did not recognize the Confederacy as a nation. For a time, Great Britain, France, and Spain seemed likely to recognize the Confederate States, but failed to do so for a variety of economic, political, and military reasons. The Emancipation Proclamation, issued by Lincoln in 1862, made the Union cause more definitely a crusade against slavery and won widespread popular support abroad. Without diplomatic recognition, it was impossible for the South to obtain badly needed aid from foreign governments—a major factor in the Confederacy's defeat.