The Proclamation turned foreign popular opinion in favor of the Union for its new commitment to end slavery. That shift ended the Confederacy’s hopes of gaining official recognition, particularly from the United Kingdom. If Britain or France, both of which had already abolished slavery, were to support the Confederacy, they would be supporting slavery.

Prior to Lincoln’s decree, Britain’s actions had favored the Confederacy, especially in its construction of warships such as the CSS Alabama and CSS Florida. As Henry Adams noted, “The Emancipation Proclamation has done more for us than all our former victories and all our diplomacy.” Giuseppe Garibaldi hailed Lincoln as “the heir of the aspirations of John Brown”. Alan Van Dyke, a representative for workers from Manchester, England, wrote to Lincoln saying, “We joyfully honor you for many decisive steps toward practically exemplifying your belief in the words of your great founders: ‘All men are created free and equal.’” The Emancipation Proclamation served to ease tensions with Europe over the North’s determination to defeat the South at all costs.