From VOA Learning English, this is The Making of a Nation. I'm Kelly Jean Kelly.

And I'm Christopher Cruise.

The Civil War began in 1861 as a struggle over whether states had the right to leave the Union. President Abraham Lincoln firmly believed that a state did not have that right. And he declared war on the southern states that tried to leave.

But the fight to preserve the nation was going badly. By summer of 1862, Union troops had not won a decisive victory in Virginia, the heart of the Confederacy. And the war was losing support with politicians and the public in the north. President Lincoln had to do something to guarantee their continued support.

Finally, in September 1862, the Union successfully stopped the Confederate invasion of Maryland. The armies of Union general George McClellan and Confederate general Robert E. Lee battled near Antietam Creek. Almost 100,000 men fought. More than 23,000 were killed, wounded or missing.

Antietam was a violent, savage battle -- the bloodiest one-day battle in American history. But the North's victory there made it easier for Abraham Lincoln to make an important announcement.

Lincoln decided to recognize that slavery was, in fact, a major issue in the war. On September 22, 1862, he announced a new policy on slavery in the rebel southern states. His announcement became known as the Emancipation Proclamation.

American newspapers printed the Emancipation Proclamation. This is what it said:

I, Abraham Lincoln, president of the United States and commander in chief of the Army and Navy, do hereby declare that on the first day of January, 1863, all persons held as slaves within any state then in rebellion against the United States, shall then become and be forever free.

The government of the United States, including the military and naval forces, will recognize and protect the freedom of such persons, and will interfere in no way with any efforts they may make for their actual freedom.

The Emancipation Proclamation freed the slaves in states held by the Confederates. For political reasons, the proclamation did not free slaves in the states that supported the Union. Nor did it free slaves in the areas around Norfolk, Virginia, and New Orleans, Louisiana.

Lincoln personally agreed that all slaves should be freed. But he did not believe that the Constitution gave him that power. He said the Emancipation Proclamation was a military measure made under his wartime powers as commander in chief. As such, it was legal only in enemy territory. He hoped the emancipation of slaves in all the states could be done slowly, during peacetime.

People in the South were furious about the proclamation. Southern newspapers accused the president of trying to create a slave rebellion in states he could not occupy with troops.

In the North, most people cheered the new policy. The Emancipation Proclamation changed the nature of the Civil War. No longer was it a struggle over southern rights. Now it was a struggle for human freedom.

I'm Kelly Jean Kelly.

And I'm Christopher Cruise.

This is The Making of a Nation with VOA Learning English.