President Lincoln wanted to encourage Northerners to keep fighting against the South, if that a reason, then he must have misunderstood why Northerners were going to risk their lives. It was a patriotic duty to preserve the Union. If that were not so, then prior to the war, there would have been mass demonstrations led by abolitionists to free slaves. There were no such mass demonstrations.
To encourage African Americans to join Union armies
France and Great Britain were doing just about all they wanted to do to supply the South.
to prevent britain from siding with the south
One of Abraham Lincoln's most famous acts was issuing the Emancipation Proclamation in 1862, which declared that all slaves in Confederate territory were to be set free. This proclamation played a significant role in the abolishment of slavery in the United States.
Abraham Lincoln was a president of the United States of America. He was president of the Union during the Civil War, and wrote the Emancipation Proclamation.
Lincoln is famous for holding the Union together during the Civil War, for issuing the Emancipation Proclamation, and championing the 14th Amendment.
It was important for Lincoln to wait before issuing the Emancipation Proclamation because he needed to ensure that the timing was right politically and militarily. He wanted to make sure that the proclamation would have the greatest impact and support possible.
Keeping Britain and France from helping the Confederates, by issuing the Emancipation Proclamation, turning the war into an official crusade against slavery. (If those countries intervened after that, they would have looked pro-slavery themselves.)
The Emancipation Proclaimation freed the slaves. Abraham Lincoln wrote this document to free the confederate slaves.The 13 Amendment.
The answer the question is probably looking for is "the Emancipation Proclamation", which kept Britain and France (both of which were anti-slavery, but also more or less anti-Union) from officially recognizing and possibly supporting the Confederacy.
Frederick Douglass viewed Abraham Lincoln's Emancipation Proclamation as a significant, albeit incomplete, step toward the abolition of slavery. Douglass appreciated Lincoln's moral stance and political courage in issuing the proclamation, recognizing it as a pivotal moment that transformed the Civil War into a fight for freedom. However, he also emphasized that true emancipation required not just a proclamation but also sustained effort and commitment to ensure equality and justice for African Americans. Ultimately, Douglass believed that the proclamation was a crucial, yet initial, step in the ongoing struggle for civil rights.
A diplomatic campaign to keep the four border-states from joining the Confederacy. Issuing the Emancipation Proclamation, to keep the British and French from granting recognition to the Confederacy. Promoting U.S. Grant to General-in-Chief.
The main purpose of issuing the Emancipation Proclamation was international propaganda, as it had no actual effect in either the north or the south as written. It freed no slaves in northern slave states still loyal to the Union and although it declared the slaves to be free in those states then in rebellion against the Union there was no means available to enforce it. Thus all slaves prior to the Emancipation Proclamation still remained in slavery after it. Only after the Civil War was over did Union soldiers have the ability to enforce the Emancipation Proclamation in the south. The slaves in the northern states that did not rebel still remained slaves until the Thirteenth Amendment completely abolished slavery (as the Emancipation Proclamation explicitly left them slaves to prevent having those states rebel too during the Civil War).
To stop the British from granting recognition to the Confederates and sending aid. Once Lincoln had declared the war to be an official crusade against slavery, then free nations abroad could not help the South without looking pro-slavery.