It gave Lincoln the credibility to issue the Emancipation Proclamation without making it sound like a desperate measure.
This had the effect of keeping the British from aiding the Confederates, as it would have made them look pro-slavery themselves.
It's first important to note that the slim victory by the Union at Antietam, did not prevent the British to continue aiding the Confederacy. In fact, the US went to an international court at the end of the war to press Great Britain for compensation for the damage Great Britain did by building Confederate warships, in particular, the CSS Alabama. The US won $15 million in damages from Great Britain. Antietam did, however, give Lincoln the break he needed to release his initial Emancipation Proclamation. This put the war on a different level, an placed pressure on the South. It did not however, help win the minds and hearts of the slave holding border states. Nor was the London press impressed by the proclamation, noting that slave states friendly to the Union were allowed to keep there slaves.
The battle's outcome was inconclusive, but the North claimed victory.
Unfortunately it was but it also was the South's first attack on the North that resulted in a Union victory.
Battle of Antietam (Battle of Sharpsburg) Sep 17 1862 On the day there was no clear winner on the battlefield, even though there were 23,000 casualties. But the strategic winner was the North. General Lee withdrew his troops from Maryland and was never seen there again. President Lincoln also made political capital out of the battle which helped to keep Great Britain out of the war.
Both Antietam and Gettysburg were fought in the North.
Shiloh Antietam Vicksburg Gettysburg Chattanooga
The battle's outcome was inconclusive, but the North claimed victory.
Antietam.
Until Antietam everyone thought that the North might actually loose the war. Antietam was just the victory Lincoln had been waiting for allowing him to issue the Emancipation Proclamation.
Unfortunately it was but it also was the South's first attack on the North that resulted in a Union victory.
The Union Victory in the Battle of Antietam.
Gettysburg, Vicksburg, the Battle of Chattenooga, and the Battle of Pettersburg. You could argue that that the battle of Antietam was also a key victory as it gave Abraham Lincoln the grounds to issue his preliminary emancipation proclamation, but Antietam was not a stunning victory for the North.
It was a battle fought in the North, and resulted in the most casualties in US history. It also was a defeat for Robert E. Lee who needed a victory that may have influenced Britain and France to lend aid to the Confederacy.
Antietam was the first major battle during the Civil War that actually turned the South away from attacking the North. Very few Southern forays into the North occurred after Antietam. The last, Gettysburg, ended in disaster for the South.
The second Battle of Bull Run was the large battle prior to Antietam, MD. The stunning Confederate victory at Bull Run emboldened Lee and his armies and made an invasion of the north seem possible.
According to military historians, the US Civil War Battle of Antietam was a technical draw. Nevertheless, Since the Army of Northern Virginia had to retreat back to Virginia, the people of the day considered it a victory, especially commander of the Army of the Potomac, Major General George B. McClellan. It was also important for the preliminary emancipation proclamation. Secretary of State Seward had wisely recommended to President Lincoln to wait until the North had a victory before issuing the proclamation. Lincoln took that advice and waited until the Battle of Antietam was over.Newspapers in England scoffed at the proclamation noting that the four border states which were slave states were not effected.
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Even though the battle was a tactical stalemate, Lee was forced to retreat, giving the North a strategic victory, allowing Lincoln to announce his Emancipation Proclamation.