The significance of the Emancipation Proclamation issued by President Lincoln in 1863 lies in its role in transforming the Civil War's purpose. Though it initially applied only to states in rebellion against the Union, the proclamation declared that all enslaved people in those areas were to be freed. This executive order redefined the war as a fight not only for the Union but also for human freedom, allowing the recruitment of African American soldiers into the Union Army. While it did not immediately free all enslaved people, it set a transformative precedent leading to the eventual abolition of slavery nationwide with the Thirteenth Amendment.