What does Lincoln mean the civil war is a test of the ability of the nation to long endure?

During the four years of the American Civil War, the president steered the North to victory and authored the Emancipation Proclamation, which dealt a severe blow to the institution of slavery in the U.S. Lincoln was a thoughtful and soft-spoken man who used Words sparingly but to great effect. His brilliance was captured in the Gettysburg Address, in which he movingly related the ongoing Civil War to the founding principles of America, all in less than two minutes.