The Emancipation Proclamation, issued by President Abraham Lincoln on January 1, 1863, declared that all enslaved people in Confederate states "shall be then, thenceforward, and forever free." However, its immediate impact was limited. The proclamation only applied to states in rebellion against the Union, not to slave-holding border states or areas already under Union control. As a result, it didn't immediately free any slaves in areas where the Union had authority to enforce it. Instead, it freed slaves in Confederate territories as Union armies advanced. Estimates vary, but it's believed that the Emancipation Proclamation initially freed about 50,000 slaves in Union-occupied parts of Confederate states. Over time, as the Union army progressed, the number of freed slaves grew to approximately 3.5 million by the end of the Civil War. It's important to note that the proclamation did not end slavery in the United States; that required the passage of the 13th Amendment in 1865.