The U.S. state of West Virginia was formed out of western Virginia and added to the Union as a direct result of the American Civil War, in which it became the only modern state to have declared its independence from the Confederacy. In the summer of 1861, Union troops, which included a number of newly formed Western Virginia regiments, under General George McClellan drove off Confederate troops under General Robert E. Lee at the Battle of Philippi in Barbour County. This essentially freed Unionists in the northwestern counties of Virginia to form a functioning government of their own as a result of the Wheeling Convention. Before the admission of West Virginia as a state, the government in Wheeling formally claimed jurisdiction over all of Virginia, although from its creation it was firmly committed to the formation of a separate state.

The Emancipation Proclamation, officially Proclamation 95, was a presidential proclamation and executive order issued by United States President Abraham Lincoln on January 1, 1863, during the American Civil War. The Proclamation had the effect of changing the legal status of more than 3.5 million enslaved African Americans in the secessionist Confederate states from enslaved to free. As soon as slaves escaped the control of their enslavers, either by fleeing to Union lines or through the advance of federal troops, they were permanently free. In addition, the Proclamation allowed for former slaves to "be received into the armed service of the United States". The Emancipation Proclamation played a significant part in the end of slavery in the United States.