He needed soldiers to fight for the union to prevent the Confederacy from gaining a victory. In the link I posted, they said that Lincoln already had a draft of the emancipation proclamation ready before he published this letter.
His intention was never to free the slaves, but to preserve the union. One way to gain new soldiers was to declare the slaves of the Confederacy free.
The confederates wanted to keep slavery, the union freed the slaves. If you were a free slave in the Confederacy, who would you fight for? The side that just freed you, or the side that wants to keep enslaving you?
He needed soldiers to fight for the union to prevent the Confederacy from gaining a victory. In the link I posted, they said that Lincoln already had a draft of the emancipation proclamation ready before he published this letter.
His intention was never to free the slaves, but to preserve the union. One way to gain new soldiers was to declare the slaves of the Confederacy free.
The confederates wanted to keep slavery, the union freed the slaves. If you were a free slave in the Confederacy, who would you fight for? The side that just freed you, or the side that wants to keep enslaving you?