The Emancipation Proclamation was an executive order issued by Abraham Lincoln on January 1, 1863. It proclaimed the freedom of slaves in the ten Confederate states still in rebellion. It also decreed that freed slaves could be enlisted in the Union Army, thereby increasing the Union's available manpower. It was an important step towards abolishing slavery and conferring American citizenship upon ex-slaves, although the Proclamation did not actually outlaw slavery or free the slaves in the Union states that still permitted it. The Proclamation broadened the goals of the Union war effort; it made the eradication of slavery into an explicit Union goal, in addition to the reuniting of the country.
The Proclamation also prevented European forces from intervening in the war on behalf of the Confederacy. Because the Emancipation Proclamation made the abolition of slavery into a Union goal, it linked support for the Confederacy to support for slavery. As Lincoln hoped, the Proclamation swung foreign popular opinion in favor of the Union by gaining the support of European countries that had already outlawed slaver. It effectively ended the Confederacy's hopes of gaining official recognition from European heads of state.
This lesson demonstrates the importance of the immediate effects that the Emancipation Proclamation had on four major American groups: the Confederate states, the Union states, the Union Army, and black Americans.