What was the significance of the Union victory at Gettysburg in July 1863?

The Union victory at Gettysburg in July of 1863 prevented the Confederacy under Robert E. Lee from advancing further into the north. If Lee had been successful at Gettysburg, he could have pushed on to cities such as Washington, D.C. and Baltimore and forced the Union to surrender. The Confederate casualties numbered about 28,000 (the number for the Union was 25,000), inflicting damage on their forces. The battle is considered the turning point of the war, and it also gave Lincoln and the Union the political and popular support they needed to continue to fight the war. Lincoln gave his famous Gettysburg Address on the battle site in November of 1863, dedicating the country to the task of rebuilding after the war and to the task of bringing about a "new birth of freedom."